We have observed an internet access issue after the device enters idle mode on iOS 26 beta 9. Although the Ivanti Secure Access Client appears connected, users are unable to access any resources (internet or intranet) after unlocking the device from idle. When we check the log socket connection looks not disrupted, packets are tunnelled but no resource access. Split tunnel enabled and proxy PAC configured. This was observed on both iOS and iPadOS 26 beta. Steps to reproduce: Connecting to the internet, launching the Ivanti client, locking the device, and then unlocking it after a brief period of idle. The issue occurs when the VPN remains connected but no resources are accessible.

I can develop a PacketTunnelProvider on Mac with xcode. I work with my self codesign. But when I sign it with Developer ID after read https://developer.apple.com/forums/thread/737894 , it still fail when I turn on the vpn .

I’m developing a iOS VPN app, and I need to execute a task in the main app even when it’s in the background or killed state. I know the Network Extension continues running during those times. Is there a way for the extension to immediately notify the app or trigger a task on the app side?

https://developer.apple.com/forums/thread/707294 General: Forums subtopic: App & System Services > Networking DevForums tag: Network Extension Network Extension framework documentation Routing your VPN network traffic article Filtering traffic by URL sample code Filtering Network Traffic sample code TN3120 Expected use cases for Network Extension packet tunnel providers technote TN3134 Network Extension provider deployment technote TN3165 Packet Filter is not API technote Network Extension and VPN Glossary forums post Debugging a Network Extension Provider forums post Exporting a Developer ID Network Extension forums post Network Extension vs ad hoc techniques on macOS forums post Network Extension Provider Packaging forums post NWEndpoint History and Advice forums post Extra-ordinary Networking forums post Wi-Fi management: Wi-Fi Fundamentals forums post TN3111 iOS Wi-Fi API overview technote How to modernize your captive network developer news post iOS Network Signal Strength forums post See also Networking Resources. Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com"

This is a topic that’s come up a few times on the forums, so I thought I’d write up a summary of the issues I’m aware of. If you have questions or comments, start a new thread in the App & System Services > Networking subtopic and tag it with Network Extension. That way I’ll be sure to see it go by. Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com" Network Extension Provider Packaging There are two ways to package a network extension provider: App extension ( appex ) System extension ( sysex ) Different provider types support different packaging on different platforms. See TN3134 Network Extension provider deployment for the details. Some providers, most notably packet tunnel providers on macOS, support both appex and sysex packaging. Sysex packaging has a number of advantages: It supports direct distribution, using Developer ID signing. It better matches the networking stack on macOS. An appex is tied to the logged in user, whereas a sysex, and the networking stack itself, is global to the system as a whole. Given that, it generally makes sense to package your Network Extension (NE) provider as a sysex on macOS. If you’re creating a new product that’s fine, but if you have an existing iOS product that you want to bring to macOS, you have to account for the differences brought on by the move to sysex packaging. Similarly, if you have an existing sysex product on macOS that you want to bring to iOS, you have to account for the appex packaging. This post summarises those changes. Keep the following in mind while reading this post: The information here applies to all NE providers that can be packaged as either an appex or a sysex. When this post uses a specific provider type in an example, it’s just an example. Unless otherwise noted, any information about iOS also applies to iPadOS, tvOS, and visionOS. Process Lifecycle With appex packaging, the system typically starts a new process for each instance of your NE provider. For example, with a packet tunnel provider: When the users starts the VPN, the system creates a process and then instantiates and starts the NE provider in that process. When the user stops the VPN, the system stops the NE provider and then terminates the process running it. If the user starts the VPN again, the system creates an entirely new process and instantiates and starts the NE provider in that. In contrast, with sysex packaging there’s typically a single process that runs all off the sysex’s NE providers. Returning to the packet tunnel provider example: When the users starts the VPN, the system instantiates and starts the NE provider in the sysex process. When the user stops the VPN, the system stops and deallocates the NE provider instances, but leaves the sysex process running. If the user starts the VPN again, the system instantiates and starts a new instances of the NE provider in the sysex process. This lifecycle reflects how the system runs the NE provider, which in turn has important consequences on what the NE provider can do: An appex acts like a launchd agent [1], in that it runs in a user context and has access to that user’s state. A sysex is effectively a launchd daemon. It runs in a context that’s global to the system as a whole. It does not have access to any single user’s state. Indeed, there might be no user logged in, or multiple users logged in. The rest of this post explores specific consequences of the NE provider lifecycle. [1] It’s not actually run as a launchd agent. Rather, there’s a system launchd agent that acts as the host for the app extension. App Groups With an app extension, the app extension and its container app run as the same user. Thus it’s trivial to share state between them using an app group container. Note When talking about extensions on Apple platforms, the container app is the app in which the extension is embedded and the host app is the app using the extension. For network extensions the host app is the system itself. That’s not the case with a system extension. The system extension runs as root whereas the container app runs an the user who launched it. While both programs can claim access to the same app group, the app group container location they receive will be different. For the system extension that location will be inside the home directory for the root user. For the container app the location will be inside the home directory of the user who launched it. This does not mean that app groups are useless in a Network Extension app. App groups are also a factor in communicating between the container app and its extensions, the subject of the next section. IMPORTANT App groups have a long and complex history on macOS. For the full story, see App Groups: macOS vs iOS: Working Towards Harmony. Communicating with Extensions With an app extension there are two communication options: App-provider messages App groups App-provider messages are supported by NE directly. In the container app, send a message to the provider by calling sendProviderMessage(_:responseHandler:) method. In the appex, receive that message by overriding the handleAppMessage(_:completionHandler:) method. An appex can also implement inter-process communication (IPC) using various system IPC primitives. Both the container app and the appex claim access to the app group via the com.apple.security.application-groups entitlement. They can then set up IPC using various APIs, as explain in the documentation for that entitlement. With a system extension the story is very different. App-provider messages are supported, but they are rarely used. Rather, most products use XPC for their communication. In the sysex, publish a named XPC endpoint by setting the NEMachServiceName property in its Info.plist. Listen for XPC connections on that endpoint using the XPC API of your choice. Note For more information about the available XPC APIs, see XPC Resources. In the container app, connect to that named XPC endpoint using the XPC Mach service name API. For example, with NSXPCConnection, initialise the connection with init(machServiceName:options:), passing in the string from NEMachServiceName. To maximise security, set the .privileged flag. Note XPC Resources has a link to a post that explains why this flag is important. If the container app is sandboxed — necessary if you ship on the Mac App Store — then the endpoint name must be prefixed by an app group ID that’s accessible to that app, lest the App Sandbox deny the connection. See app groups documentation for the specifics. When implementing an XPC listener in your sysex, keep in mind that: Your sysex’s named XPC endpoint is registered in the global namespace. Any process on the system can open a connection to it [1]. Your XPC listener must be prepared for this. If you want to restrict connections to just your container app, see XPC Resources for a link to a post that explains how to do that. Your sysex only gets one named XPC endpoint, and thus one XPC listener. If your sysex includes multiple NE providers, take that into account when you design your XPC protocol. [1] Assuming that connection isn’t blocked by some other mechanism, like the App Sandbox. Inter-provider Communication A sysex can include multiple types of NE providers. For example, a single sysex might include a content filter and a DNS proxy provider. In that case the system instantiates all of the NE providers in the same sysex process. These instances can communicate without using IPC, for example, by storing shared state in global variables (with suitable locking, of course). It’s also possible for a single container app to contain multiple sysexen, each including a single NE provider. In that case the system instantiates the NE providers in separate processes, one for each sysex. If these providers need to communicate, they have to use IPC. In the appex case, the system instantiates each provider in its own process. If two providers need to communicate, they have to use IPC. Managing Secrets An appex runs in a user context and thus can store secrets, like VPN credentials, in the keychain. On macOS this includes both the data protection keychain and the file-based keychain. It can also use a keychain access group to share secrets with its container app. See Sharing access to keychain items among a collection of apps. Note If you’re not familiar with the different types of keychain available on macOS, see TN3137 On Mac keychain APIs and implementations. A sysex runs in the global context and thus doesn’t have access to user state. It also doesn’t have access to the data protection keychain. It must use the file-based keychain, and specifically the System keychain. That means there’s no good way to share secrets with the container app. Instead, do all your keychain operations in the sysex. If the container app needs to work with a secret, have it pass that request to the sysex via IPC. For example, if the user wants to use a digital identity as a VPN credential, have the container app get the PKCS#12 data and password and then pass that to the sysex so that it can import the digital identity into the keychain. Memory Limits iOS imposes strict memory limits an NE provider appexen [1]. macOS imposes no memory limits on NE provider appexen or sysexen. [1] While these limits are not documented officially, you can get a rough handle on the current limits by reading the posts in this thread. Frameworks If you want to share code between a Mac app and its embedded appex, use a structure like this: MyApp.app/ Contents/ MacOS/ MyApp PlugIns/ MyExtension.appex/ Contents/ MacOS/ MyExtension … Frameworks/ MyFramework.framework/ … There’s one copy of the framework, in the app’s Frameworks directory, and both the app and the appex reference it. This approach works for an appex because the system always loads the appex from your app’s bundle. It does not work for a sysex. When you activate a sysex, the system copies it to a protected location. If that sysex references a framework in its container app, it will fail to start because that framework isn’t copied along with the sysex. The solution is to structure your app like this: MyApp.app/ Contents/ MacOS/ MyApp Library/ SystemExtensions/ MyExtension.systemextension/ Contents/ MacOS/ MyExtension Frameworks/ MyFramework.framework/ … … That is, have both the app and the sysex load the framework from the sysex’s Frameworks directory. When the system copies the sysex to its protected location, it’ll also copy the framework, allowing the sysex to load it. To make this work you have to change the default rpath configuration set up by Xcode. Read Dynamic Library Standard Setup for Apps to learn how that works and then tweak things so that: The framework is embedded in the sysex, not the container app. The container app has an additional LC_RPATH load command for the sysex’s Frameworks directory (@executable_path/../Library/SystemExtensions/MyExtension.systemextension/Contents/Frameworks). The sysex’s LC_RPATH load command doesn’t reference the container app’s Frameworks directory (@executable_path/../../../../Frameworks) but instead points to the sysex’s Framweorks directory (@executable_path/../Frameworks).

I am running a full-tunnel VPN using a Packet Tunnel Provider. During VPN setup, we configure DNS setting with specific DNS servers for all domains to be used by the tunnel. However, our project requires DNS resolution for every domain from both the VPN-provided DNS servers and the ISP’s DNS servers. When I attempt to use c-ares or other third-party libraries to resolve domains via the ISP DNS servers, these libraries only detect and use the VPN DNS servers instead. As a result, all queries fail. Is there a way on iOS to programmatically determine the ISP DNS servers while a full-tunnel VPN is active, or a system API that allows DNS queries to be explicitly resolved using the ISP’s DNS servers?

Hi! When starting my app which is loading a Content Filter Network Extension I am getting the following error : sysextd: <bundle_id> : extension failed category property check: extensions belonging to the com.apple.system_extension.endpoint_security category require a later version of operating system to launch ... OSSystemExtensionRequest didFailWithError for <bundle_id> : The operation couldn’t be completed. (OSSystemExtensionErrorDomain error 9.) This is happening on a VM running Sonoma 14.7.8. I upgraded the VM to the latest available OS and the system extension is loading just fine. My question is : reading the documentation, I understand that the Network Extensions are supported starting with macOS 10.10+. Why is this not working on my Sonoma 14.7.8 VM?

Starting with macOS 15 (Sequoia), applications that perform network discovery operations now trigger a permission prompt: "Allow [AppName] to find devices on local networks". I am using sysctl() with NET_RT_FLAGS and RTF_LLINFO to access the ARP table and retrieve gateway MAC addresses: int mib[6]; mib[0] = CTL_NET; mib[1] = PF_ROUTE; mib[2] = 0; mib[3] = AF_INET; mib[4] = NET_RT_FLAGS; mib[5] = RTF_LLINFO; // This flag accesses ARP table entries if (sysctl(mib, 6, buf, &amp;needed, NULL, 0) &lt; 0) return nil; From my testing, the Local Network Access prompt does not always appear. It looks like if the MAC address is already cached in the ARP table, no prompt is shown, and the prompt only appears when the system needs to resolve a new MAC address. Is this correct behavior? Does ARP resolution by itself triggering the prompt?

Hi! I'm trying to prototype a macOS app related to wifi features. The main hiccup I've encountered is "Connect to a saved network without re-entering the network password". So far I've been unsuccessful in this without entering the password manually each time asking the user for authentication to access the saved network in keychain I read somewhere on the internet that CWInterface.associate would use saved credentials automatically if you gave a nil password, but my attempts have proven that to be false. Is this not currently available because it raises security concerns, or it just hasn't been considered? Or am I missing a way to do this? I don't need access to the credentials, just for the system to connect for me.

As per : TN3120: Expected use cases for Network Extension packet tunnel providers | Apple Developer Documentation It is clear that Packets that are read from NEPacketTunnelFlow are meant to be sent over a tunnel connection to a remote server for injection into a remote network. They are not meant to be dropped or re-injected back into the system. In my usecase: NEPacketTunnelProvider is separate process. which reads the packet using packetFlow.readPacketObjects Send it over to other process i.e privileged helper(Non-bundle/command line tool/non sandboxed) via UDS IPC. Helpers send to to remote tunnel and return back the packet to NEPacketTunnelFlow via same IPC. NEPacketTunnelProvider uses packetFlow.writePacketObjects to inject packets. Things works fine. We don't distribute it via Appstore. We are now attempting to implement a on device bypass mechanism from helper tool side. Could you please suggest if there is any approach I could try, even if it involves proceeding at my own risk?

We are developing a custom vpn client using Packet Tunnel Provider extension. Our VPN use Client Certificate authentication. Certificates need to be delivered to device using MDM. We plan to deliver certificates and other settings using configuration profiles with com.apple.vpn.managed and com.apple.security.pkcs12 payloads. There are some things we do not understand: What entitlements do we need? Do we need additional entitlements except com.apple.developer.networkingextension and com.apple.managed.vpn.shared? What is the process to get com.apple.managed.vpn.shared entitlement? Is ADP (not ADEP) enough for such application?

At WWDC 2015 Apple announced two major enhancements to the Network Extension framework: Network Extension providers — These are app extensions that let you insert your code at various points within the networking stack, including: Packet tunnels via NEPacketTunnelProvider App proxies via NEAppProxyProvider Content filters via NEFilterDataProvider and NEFilterControlProvider Hotspot Helper (NEHotspotHelper) — This allows you to create an app that assists the user in navigating a hotspot (a Wi-Fi network where the user must interact with the network in order to get access to the wider Internet). Originally, using any of these facilities required authorisation from Apple. Specifically, you had to apply for, and be granted access to, a managed capability. In Nov 2016 this policy changed for Network Extension providers. Any developer can now use the Network Extension provider capability like they would any other capability. There is one exception to this rule: Network Extension app push providers, introduced by iOS 14 in 2020, still requires that Apple authorise the use of a managed capability. To apply for that, follow the link in Local push connectivity. Also, the situation with Hotspot Helpers remains the same: Using a Hotspot Helper, requires that Apple authorise that use via a managed capability. To apply for that, follow the link in Hotspot helper. IMPORTANT Pay attention to this quote from the documentation: NEHotspotHelper is only useful for hotspot integration. There are both technical and business restrictions that prevent it from being used for other tasks, such as accessory integration or Wi-Fi based location. The rest of this document answers some frequently asked questions about the Nov 2016 change. #1 — Has there been any change to the OS itself? No, this change only affects the process by which you get the capabilities you need in order to use existing Network Extension framework facilities. Previously these were managed capabilities, meaning their use was authorised by Apple. Now, except for app push providers and Hotspot Helper, you can enable the necessary capabilities using Xcode’s Signing & Capabilities editor or the Developer website. IMPORTANT Some Network Extension providers have other restrictions on their use. For example, a content filter can only be used on a supervised device. These restrictions are unchanged. See TN3134 Network Extension provider deployment for the details. #2 — How exactly do I enable the Network Extension provider capability? In the Signing & Capabilities editor, add the Network Extensions capability and then check the box that matches the provider you’re creating. In the Certificates, Identifiers & Profiles section of the Developer website, when you add or edit an App ID, you’ll see a new capability listed, Network Extensions. Enable that capability in your App ID and then regenerate the provisioning profiles based on that App ID. A newly generated profile will include the com.apple.developer.networking.networkextension entitlement in its allowlist; this is an array with an entry for each of the supported Network Extension providers. To confirm that this is present, dump the profile as shown below. $ security cms -D -i NETest.mobileprovision … <plist version="1.0"> <dict> … <key>Entitlements</key> <dict> <key>com.apple.developer.networking.networkextension</key> <array> <string>packet-tunnel-provider</string> <string>content-filter-provider</string> <string>app-proxy-provider</string> … and so on … </array> … </dict> … </dict> </plist> #3 — I normally use Xcode’s Signing & Capabilities editor to manage my entitlements. Do I have to use the Developer website for this? No. Xcode 11 and later support this capability in the Signing & Capabilities tab of the target editor (r. 28568128 ). #4 — Can I still use Xcode’s “Automatically manage signing” option? Yes. Once you modify your App ID to add the Network Extension provider capability, Xcode’s automatic code signing support will include the entitlement in the allowlist of any profiles that it generates based on that App ID. #5 — What should I do if I previously applied for the Network Extension provider managed capability and I’m still waiting for a reply? Consider your current application cancelled, and use the new process described above. #6 — What should I do if I previously applied for the Hotspot Helper managed capability and I’m still waiting for a reply? Apple will continue to process Hotspot Helper managed capability requests and respond to you in due course. #7 — What if I previously applied for both Network Extension provider and Hotspot Helper managed capabilities? Apple will ignore your request for the Network Extension provider managed capability and process it as if you’d only asked for the Hotspot Helper managed capability. #8 — On the Mac, can Developer ID apps host Network Extension providers? Yes, but there are some caveats: This only works on macOS 10.15 or later. Your Network Extension provider must be packaged as a system extension, not an app extension. You must use the *-systemextension values for the Network Extension entitlement (com.apple.developer.networking.networkextension). For more on this, see Exporting a Developer ID Network Extension. #9 — After moving to the new process, my app no longer has access to the com.apple.managed.vpn.shared keychain access group. How can I regain that access? Access to this keychain access group requires another managed capability. If you need that, please open a DTS code-level support request and we’ll take things from there. IMPORTANT This capability is only necessary if your VPN supports configuration via a configuration profile and needs to access credentials from that profile (as discussed in the Profile Configuration section of the NETunnelProviderManager Reference). Many VPN apps don’t need this facility. Opening a DTS tech support incident (TSI) will consume a TSI asset. However, as this is not a technical issue but an administrative one, we’ll assign a replacement TSI asset back to your account. If you were previously granted the Network Extension managed capability (via the process in place before Nov 2016), make sure you mention that; restoring your access to the com.apple.managed.vpn.shared keychain access group should be straightforward in that case. Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com" Revision History 2025-09-12 Adopted the code-level support request terminology. Made other minor editorial changes. 2023-01-11 Added a discussion of Network Extension app push providers. Added a link to Exporting a Developer ID Network Extension. Added a link to TN3134. Made significant editorial changes. 2020-02-27 Fixed the formatting. Updated FAQ#3. Made minor editorial changes. 2020-02-16 Updated FAQ#8 to account for recent changes. Updated FAQ#3 to account for recent Xcode changes. Made other editorial changes. 2016-01-25 Added FAQ#9. 2016-01-6 Added FAQ#8. 2016-11-11 Added FAQ#5, FAQ#6 and FAQ#7. 2016-11-11 First posted.

We’ve noticed an issue where after running a network extension, if the phone’s language is changed the Locale.preferredLanguages array is not updated and still returns the old array. It only returns the updated array when the app is reinstalled or the phone is restarted. This is unlike the app itself where using the same Locale.preferredLanguages API immediately returns the updated array. We think this issue is also the cause of notifications that are sent by the network extension being in the previous language as long as the app isn’t reinstalled or the phone is restarted, despite our Localizable file having localised strings for the new language. Feedback ID: FB20086051 The feedback report includes a sample project with steps on how to reproduce the issue.

I'm seeing fully reproducible issues with URLSession on iOS 18.4 RC Simulator running from Xcode 16.3 RC. URLSession seems to get into a broken state after a second app run. The following sample succeeds in fetching the JSON on first app run but when the app is closed and ran again it fails with one of these errors: Error: Error Domain=NSURLErrorDomain Code=-1005 "The network connection was lost." Error: Error Domain=NSURLErrorDomain Code=-1001 "The request timed out." I'm wondering if this something related to my OS setup or is this due to internal URLSession changes in iOS 18.4. Already submitted as FB17006003. Sample code attached below: import SwiftUI @main struct NetworkIssue18_4App: App { var body: some Scene { WindowGroup { ContentView() } } } struct ContentView: View { @State private var message: String = "" var body: some View { VStack { Text(message) Button("Try Again") { Task { await fetch() } } } .task { await fetch() } } private func fetch() async { message = "Loading..." let url = URL(string: "https://poetrydb.org/title/Ozymandias/lines.json")! let session = URLSession.shared do { let response = try await session.data(from: url) print("Response: \(response)") message = "Success, data length: \(response.0.count)" } catch { print("Error: \(error)") message = "Error: \(error.localizedDescription)" } } }

I'm having a lot of trouble just getting a basic network extension startup, I have a main application that creates the configuration and requests the app extension based network extension to launch. The network extension implements a NEPacketTunnelProvider and the application doesn't receive an error when starting the tunnel but when I inspect the networkextension system logs, I keep getting errors and the network extension itself doesn't appear to start nor does it log anything. log stream --predicate 'subsystem == "com.apple.networkextension"' neagent: (NetworkExtension) [com.apple.networkextension:] Extension request with extension $(BUNDLE_ID) started with identifier (null) neagent: (NetworkExtension) [com.apple.networkextension:] Failed to start extension $(BUNDLE_ID): Error Domain=NSCocoaErrorDomain Code=4097 "connection to service named $(BUNDLE_ID)" UserInfo={NSDebugDescription=connection to service named $(BUNDLE_ID)} nesessionmanager: [com.apple.networkextension:] Validation failed - no audit tokens nesessionmanager: [com.apple.networkextension:] NEVPNTunnelPlugin($(BUNDLE_ID)[inactive]): Validation of the extension failed The network extension is written in Objective-C as it needs to integrate with another language. It's not entirely clear what kind of executable the network extension is meant to be, is it meant to have a main entrypoint, or is it supposed to be a shared library / bundle?

Upgrade iOS to 18.5, then install app in Xcode and grant permissions to send UDP but it won't work. Then restart device, open this installed app and send UDP again and this time it becomes OK. Repeat these steps and it all goes well. The UDP pod I use in app is CocoaAsyncSocket. The same thing happens on iPhone 14 Plus and 16 Pro, both iOS 18.5. How to explain this phenomenon, thanks for your help in advance.

Please ask Apple to provide an interface for sending follow-ups like Samsung's WiFi Aware.

Description : Our app helps users connect to Wi-Fi hotspots. We are trying to adapt our code to iOS 26 Hotspot Authentication and Hotspot Evaluation application extensions. When filtering hotspots in the filterScanList callback, we need to fetch support information from a remote server to determine which hotspots are supported. However, attempts to use URLSession or NWTCPConnection in the extension always fail. When accessing a URL (e.g., https://www.example.com), the network log shows: Error Domain=NSURLErrorDomain Code=-1003 "A server with the specified hostname could not be found." When accessing a raw IP address, the log shows: [1: Operation not permitted] Interestingly, NWPathMonitor shows the network path as satisfied, indicating that the network is reachable. Question: Are there any missing permissions or misconfigurations on our side, or are we using the wrong approach? Is there an official recommended way to perform network requests from an NEHotspotEvaluationProvider extension?

Around 8/23/25, I installed macOS 15.6.1 on my work Mac. After this I can no longer log the application I am working on into our backend servers. My work Mac is running Palo Alto Global Protect VPN software along with a bunch of associated security software to lock down my computer. I had no issues with connecting to our backend servers behind the firewall before the macOS update and nothing has changed in the source code related to this. When I send the username the network call just hangs and never times out. On the other hand, if I turn off the VPN and point to the production environment the call succeeds with no problems. Any Ideas?

iOS Development environment Xcode 16.4, macOS 15.6.1 (24G90) Run-time configuration: iOS 17.2+ Short Description After having successfully established an NWConnection (either as UDP or TCP), and subsequently receiving the error code: UDP Connection failed: 57 The operation couldn't be completed. (Network.NWError error 57 - Socket is not connected), available Interfaces: [enO] via NWConnection.stateUpdateHandler = { (newState) in ... } while newState == .failed the data connection does not restart by itself once cellular (RF) telephony coverage is established again. Detailed Description Context: my app has a continuous cellular data connection while in use. Either a UDP or a TCP connection is established depending on the user settings. The setup data connection works fine until the data connection gets disconnected by loss of connection to a available cellular phone base station. This disconnection simply occurs in very poor UMTS or GSM cellular phone coverage. This is totally normal behavior in bad reception areas like in mountains with signal loss. STEPS TO REPRODUCE Pre-condition App is running with active data connection. Action iPhone does loss the cellular data connection previously setup. Typically reported as network error code 57. Observed The programmed connection.stateUpdateHandler() is called in network connection state '.failed' (OK). The self-programmed data re-connection includes: a call to self.connection.cancel() a call to self.setupUDPConnection() or self.setupConnection() depending on the user settings to re-establish an operative data connection. However, the iPhone's UMTS/GSM network data (re-)connection state is not properly identified/notified via NWConnection API. There's no further network state notification by means of NWConnection even though the iPhone has recovered a cellular data network. Expected The iPhone or any other means automatically reconnects the interrupted data connection on its own. The connection.stateUpdateHandler() is called at time of the device's networking data connection (RF) recovering, subsequently to a connection state failed with error code 57, as the RF module is continuously (independently from the app) for available telephony networks. QUESTION How to systematically/properly detect a cellular phone data network reconnection readiness in order to causally reinitialize the NWConnection data connection available used in app. Relevant code extract Setup UDP connection (or similarly setup a TCP connection) func setupUDPConnection() { let udp = NWProtocolUDP.Options.init() udp.preferNoChecksum = false let params = NWParameters.init(dtls: nil, udp: udp) params.serviceClass = .responsiveData // service type for medium-delay tolerant, elastic and inelastic flow, bursty, and long-lived connections connection = NWConnection(host: NWEndpoint.Host.name(AppConstant.Web.urlWebSafeSky, nil), port: NWEndpoint.Port(rawValue: AppConstant.Web.urlWebSafeSkyPort)!, using: params) connection.stateUpdateHandler = { (newState) in switch (newState) { case .ready: //print("UDP Socket State: Ready") self.receiveUDPConnection(). // data reception works fine until network loss break case .setup: //print("UDP Socket State: Setup") break case .cancelled: //print("UDP Socket State: Cancelled") break case .preparing: //print("UDP Socket State: Preparing") break case .waiting(let error): Logger.logMessage(message: "UDP Connection waiting: "+error.errorCode.description+" \(error.localizedDescription), available Interfaces: \(self.connection.currentPath!.availableInterfaces.description)", LoggerLevels.Error) break case .failed(let error): Logger.logMessage(message: "UDP Connection failed: "+error.errorCode.description+" \(error.localizedDescription), available Interfaces: \(self.connection.currentPath!.availableInterfaces.description)", LoggerLevels.Error) // data connection retry (expecting network transport layer to be available) self.reConnectionServer() break default: //print("UDP Socket State: Waiting or Failed") break } self.handleStateChange() } connection.start(queue: queue) } Handling of network data connection loss private func reConnectionServer() { self.connection.cancel() // Re Init Connection - Give a little time to network recovery let delayInSec = 30.0. // expecting actually a notification for network data connection availability, instead of a time-triggered retry self.queue.asyncAfter(deadline: .now() + delayInSec) { switch NetworkConnectionType { case 1: self.setupUDPConnection() // UDP break case 2: self.setupConnection() // TCP break default: break } } } Does it necessarily require the use of CoreTelephony class CTTelephonyNetworkInfo or class CTCellularData to get notifications of changes to the user’s cellular service provider?