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Explore the networking protocols and technologies used by the device to connect to Wi-Fi networks, Bluetooth devices, and cellular data services.

Networking Documentation

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Internet stops working after idle time when using VPN on iOS 26 beta
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.
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423
Sep ’25
iPhone failure to get IP from DHCP on WiFi model RN171
I have written an App which extracts data, over WiFi, from an instrument that creates its own WiFi Hotspot. The instrument provides no internet connection. The iPad version of this App is connects fine and is assigned an IP address by DHCP server running on a MicroChip RN171 wifi module. iOS assigns an obscure IP address on a completely different subnet. I understand this is iOS' way of "Complaining" that is wasn't assigned an IP address. Consequently in the case of the iPhone I am forced to manually assign an IP address for the iPhone, the mask and the gateway. Only then is the connection successful. Anyone know why the iPhone won't talk DHCP to a WiFi module not connected to the internet? Are there perhaps some parameters that I need to adjust on either the iPhone or WiFi module?
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196
May ’25
App Extension Network Extension - failed to start, signature check failed
Howdy, I've been developing a packet tunnel extension meant to run on iOS and MacOS. For development I'm using xcodegen + xcodebuild to assemble a bunch of swift and rust code together. I'm moving from direct TUN device management on Mac to shipping a Network Extension (appex). With that move I noticed that on some mac laptops NE fails to start completely, whilst on others everything works fine. I'm using CODE_SIGN_STYLE: Automatic, Apple IDs are within the same team, all devices are registered as dev devices. Signing dev certificates, managed by xcode. Some suspicious logs: (NetworkExtension) [com.apple.networkextension:] Signature check failed: code failed to satisfy specified code requirement(s) ... (NetworkExtension) [com.apple.networkextension:] Provider is not signed with a Developer ID certificate What could be the issue? Where those inconsistencies across devices might come from?
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287
Nov ’25
Unable to send/receive IPv6 Mutlicast packets on NWConnectionGroup using Apple NF
Hello Everyone, I am currently using macOS 15.5 and XCode 16.4. I am using the following code to send/receive multicast packets on multicast group ff02::1 and port 49153 using Apple NF's NWConnectionGroup. import Network import Foundation // Creating a mutlicast group endpoint let multicastIPv6GroupEndpoint: NWEndpoint = NWEndpoint.hostPort(host: NWEndpoint.Host.ipv6(IPv6Address("ff02::1")!), port: NWEndpoint.Port("49153")!) do { let multicastGroupDescriptor: NWMulticastGroup = try NWMulticastGroup (for: [multicastIPv6GroupEndpoint]) let multicastConnectionGroupDescriptor = NWConnectionGroup (with: multicastGroupDescriptor, using: .udp) multicastConnectionGroupDescriptor.stateUpdateHandler = { state in print ("🕰️ Connection Group state: \(state)") if state == .ready { multicastConnectionGroupDescriptor.send (content: "👋🏻 Hello from the Mac 💻".data (using: .utf8)) { err in print ("➡️ Now, I am trying to send some messages.") if let err = err { print ("💥 Error sending multicast message: \(err)") } else { print ("🌚 Initial multicast message sent") } } } } multicastConnectionGroupDescriptor.setReceiveHandler { message, content, isComplete in if let content = content, let messageString = String (data: content, encoding: .utf8) { print ("⬅️ Received message: \(messageString)") } } multicastConnectionGroupDescriptor.start (queue: .global()) } catch { print ("💥 Error while creating Multicast Group: \(error)") } RunLoop.main.run() I am able to successfully create a NWConnectionGroup without any warnings/errors. The issue occurs when the stateUpdateHandler's callback gets invoked. It first gives me this warning: nw_listener_socket_inbox_create_socket IPV6_LEAVE_GROUP ff02::1.49153 failed [49: Can't assign requested address But then it shows me that the state is ready: 🕰️ Connection Group state: ready After this, when the send is performed, it gives me a bunch of errros: nw_endpoint_flow_failed_with_error [C1 ff02::1.49153 waiting parent-flow (unsatisfied (Local network prohibited), interface: en0[802.11], ipv4, ipv6, uses wifi)] already failing, returning nw_socket_connect [C1:1] connectx(7, [srcif=0, srcaddr=::.62838, dstaddr=ff02::1.49153], SAE_ASSOCID_ANY, 0, NULL, 0, NULL, SAE_CONNID_ANY) failed: [48: Address already in use] nw_socket_connect [C1:1] connectx failed (fd 7) [48: Address already in use] nw_socket_connect connectx failed [48: Address already in use] nw_endpoint_flow_failed_with_error [C1 ff02::1.49153 in_progress socket-flow (satisfied (Path is satisfied), interface: en0[802.11], ipv4, ipv6, dns, uses wifi)] already failing, returning There is no other background process running on the same port. I tried using different ports as well as multicast groups but the same error persists. The same code works fine for an IPv4 multicast group. I have following questions: Why am I getting these errors specifically for IPv6 multicast group but not for IPv4 multicast group? Are there any configurations that needed to be done in order to get this working?
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257
Jun ’25
Crashes in NEFilterPacketInterpose createChannel
Hello, Our users are seeing random crashes in our packet filter system extension on macOS. Any help pointing me in the right direction to either avoid the issue or fix it would be greatly appreciated. Attached is the crash log. Thank you. packetfilter.crash Crashed Thread: 2 Dispatch queue: com.apple.network.connections Exception Type: EXC_BAD_ACCESS (SIGBUS) Exception Codes: KERN_PROTECTION_FAILURE at 0x0000000112918700 Exception Note: EXC_CORPSE_NOTIFY Termination Signal: Bus error: 10 Termination Reason: Namespace SIGNAL, Code 0xa Terminating Process: exc handler [40687] ... Thread 2 Crashed:: Dispatch queue: com.apple.network.connections 0 libsystem_kernel.dylib 0x00007fff2089b46e os_channel_get_next_slot + 230 1 com.apple.NetworkExtension 0x00007fff2e2e2643 __40-[NEFilterPacketInterpose createChannel]_block_invoke + 560 2 libdispatch.dylib 0x00007fff20718806 _dispatch_client_callout + 8 3 libdispatch.dylib 0x00007fff2071b1b0 _dispatch_continuation_pop + 423 4 libdispatch.dylib 0x00007fff2072b564 _dispatch_source_invoke + 2061 5 libdispatch.dylib 0x00007fff20720318 _dispatch_workloop_invoke + 1784 6 libdispatch.dylib 0x00007fff20728c0d _dispatch_workloop_worker_thread + 811 7 libsystem_pthread.dylib 0x00007fff208bf45d _pthread_wqthread + 314 8 libsystem_pthread.dylib 0x00007fff208be42f start_wqthread + 15
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1.4k
Jun ’25
Local Push Connectivity - Unreliable Connection
Hi! My project has the Local Push Connectivity entitlement for a feature we have requiring us to send low-latency critical notifications over a local, private Wi-Fi network. We have our NEAppPushProvider creating a SSE connection using the Network framework with our hardware running a server. The server sends a keep-alive message every second. On an iPhone 16 with iOS 18+, the connection is reliable and remains stable for hours, regardless of whether the iOS app is in the foreground, background, or killed. One of our QA engineers has been testing on an iPhone 13 running iOS 16, and has notice shortly after locking the phone, specifically when not connected to power the device seems to turn off the Wi-Fi radio. So when the server sends a notification, it is not received. About 30s later, it seems to be back on. This happens on regular intervals. When looking at our log data, the provider does seem to be getting stopped, then restarted shortly after. The reason code is NEProviderStopReasonNoNetworkAvailable, which further validates that the network is getting dropped by the device in regular intervals. My questions are: Were there possibly silent changes to the framework between iOS versions that could be the reason we're seeing inconsistent behavior? Is there a connection type we could use, instead of SSE, that would prevent the device from disconnecting and reconnecting to the Wi-Fi network? Is there an alternative approach to allow us to maintain a persistent network connection with the extension or app?
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308
Jul ’25
ios26 beta5 VPN Profile not installing
I have a custom VPN app that uses NETunnelProviderManager to install a VPN Profile if one is not already installed. On previous iOS versions this would open the VPN Settings and ask for either the PIN, FaceID or TouchID and install the profile. With iOS 26 beta5 it opens the VPN Settings and stops. Is this a bug in iOS 26? Have there been changes to NETunnelProviderManager for iOS 26 that I'm not aware of? FYI we do the samething on macOS 26 beta5 and that works as expected.
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2
641
Aug ’25
No route to host
I upgraded my Mac to Sequoia 15.4.1 an i hat to upgrade XCode to Version 16.3. I access a MQTT Broker by an sending an mosquitto_sub request to the Broker. Now its no longer possible the request fails i granted Network permission to my App
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178
May ’25
URLCache behavior for request with different header values
Greetings, I would like to understand this URLCache behavior for two different requests to the same end point but with a different header value. Here is a code with comment explaining the behavior. // Create a request to for a url. let url = URL(string: "https://<my url>?f=json")! var request = URLRequest(url: url) // Set custom header with a value. request.setValue("myvalue", forHTTPHeaderField: "CustomField") // Send request to get the response. let (data, response) = try await URLSession.shared.data(for: request) print("data: \(String(describing: String(data: data, encoding: .utf8)))") print("response: \(response)") // Create second request to the same url but with different value of custom header field. var request2 = URLRequest(url: url) request2.setValue("newvalue", forHTTPHeaderField: "CustomField") // Check the URL cache for second request and it returns the response // of the first request even though the second request has different header value. let cachedResponse = URLCache.shared.cachedResponse(for: request2) print("cachedResponse: \(cachedResponse?.response)") Is this a bug in URLCache that request headers are not matched while returning the response? Is this an expected behavior? If yes, why?
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1.7k
Aug ’25
What is the command to list all socket filters/extensions in use?
I am in the middle of investigating an issue arising in the call to setsockopt syscall where it returns an undocumented and unexpected errno. As part of that, I'm looking for a way to list any socket content filters or any such extensions are in play on the system where this happens. To do that, I ran: systemextensionsctl list That retuns the following output: 0 extension(s) which seems to indicate there's no filters or extensions in play. However, when I do: netstat -s among other things, it shows: net_api: 2 interface filters currently attached 2 interface filters currently attached by OS 2 interface filters attached since boot 2 interface filters attached since boot by OS ... 4 socket filters currently attached 4 socket filters currently attached by OS 4 socket filters attached since boot 4 socket filters attached since boot by OS What would be the right command/tool/options that I could use to list all the socket filters/extensions (and their details) that are in use and applicable when a call to setsockopt is made from an application on that system? Edit: This is on a macosx-aarch64 with various different OS versions - 13.6.7, 14.3.1 and even 14.4.1.
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906
Aug ’25
Thread Network API not working
I'm trying to use ThreadNetwork API to manage TheradNetworks on device (following this documentation: https://developer.apple.com/documentation/threadnetwork/), but while some functions on THClient work (such as getPreferedNetwork), most don't (storeCredentials, retrieveAllCredentials). When calling these functions I get the following warning/error: Client: -[THClient getConnectionEntitlementValidity]_block_invoke - Error: -[THClient storeCredentialsForBorderAgent:activeOperationalDataSet:completion:]_block_invoke:701: - Error: Error Domain=NSCocoaErrorDomain Code=4099 "The connection to service with pid 414 named com.apple.ThreadNetwork.xpc was invalidated from this process." UserInfo={NSDebugDescription=The connection to service with pid 414 named com.apple.ThreadNetwork.xpc was invalidated from this process.} Error Domain=NSCocoaErrorDomain Code=4099 "The connection to service with pid 414 named com.apple.ThreadNetwork.xpc was invalidated from this process." UserInfo={NSDebugDescription=The connection to service with pid 414 named com.apple.ThreadNetwork.xpc was invalidated from this process.} Failed to store Thread credentials: Couldn’t communicate with a helper application. STEPS TO REPRODUCE Create new project Add Thread Network capability via Xcode UI (com.apple.developer.networking.manage-thread-network-credentials) Trigger storeCredentials let extendedMacData = "9483C451DC3E".hexadecimal let tlvHex = "0e080000000000010000000300001035060004001fffe002083c66f0dc9ef53f1c0708fdb360c72874da9905104094dce45388fd3d3426e992cbf0697b030d474c2d5332302d6e65773030310102250b04106c9f919a4da9b213764fc83f849381080c0402a0f7f8".hexadecimal // Initialize the THClient let thClient = THClient() // Store the credentials await thClient.storeCredentials(forBorderAgent: extendedMacData!, activeOperationalDataSet: tlvHex!) { error in if let error = error { print(error) print("Failed to store Thread credentials: \(error.localizedDescription)") } else { print("Successfully stored Thread credentials") } } NOTES: I tried with first calling getPreferedNetwork to initiate network permission dialog Tried adding meshcop to bojur services Tried with different release and debug build configurations
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530
Dec ’25
Completion handler blocks are not supported in background sessions
When I try to implement the new Background Task options in the same way as they show in the WWDC video (on watchOS) likes this: let config = URLSessionConfiguration.background(withIdentifier: "SESSION_ID") config.sessionSendsLaunchEvents = true let session = URLSession(configuration: config) let response = await withTaskCancellationHandler {       try? await session.data(for: request) } onCancel: {       let task = session.downloadTask(with: request))       task.resume() } I'm receiving the following error: Terminating app due to uncaught exception 'NSGenericException', reason: 'Completion handler blocks are not supported in background sessions. Use a delegate instead.' Did I forget something?
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2.7k
Apr ’25
Disable URLSession auto retry policy
We are developing an iOS application that is interacting with HTTP APIs that requires us to put a unique UUID (a nonce) as an header on every request (obviously there's more than that, but that's irrilevant to the question here). If the same nonce is sent on two subsequent requests the server returns a 412 error. We should avoid generating this kind of errors as, if repeated, they may be flagged as a malicious activity by the HTTP APIs. We are using URLSession.shared.dataTaskPublisher(for: request) to call the HTTP APIs with request being generated with the unique nonce as an header. On our field tests we are seeing a few cases of the same HTTP request (same nonce) being repeated a few seconds on after the other. Our code has some retry logic only on 401 errors, but that involves a token refresh, and this is not what we are seeing from logs. We were able to replicate this behaviour on our own device using Network Link Conditioner with very bad performance, with XCode's Network inspector attached we can be certain that two HTTP requests with identical headers are actually made automatically, the first request has an "End Reason" of "Retry", the second is "Success" with Status 412. Our questions are: can we disable this behaviour? can we provide a new request for the retry (so that we can update headers)? Thanks, Francesco
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344
Aug ’25
NetworkExtension framework problems
Case-ID: 17935956 In the NetworkExtension framework, for the NETransparentProxyProvider and NEDNSProxyProvider classes: when calling the open func writeDatagrams(_ datagrams: [Data], sentBy remoteEndpoints: [NWEndpoint]) async throwsin the NEDNSProxyProvider class, and the open func write(_ data: Data, withCompletionHandler completionHandler: @escaping @Sendable ((any Error)?) -> Void)in the NETransparentProxyProvider class, errors such as "The operation could not be completed because the flow is not connected" and "Error Domain=NEAppProxyFlowErrorDomain Code=1 "The operation could not be completed because the flow is not connected"" occur. Once this issue arises, if it occurs in the NEDNSProxyProvider, the entire system's DNS will fail to function properly; if it occurs in the NETransparentProxyProvider, the entire network will become unavailable.
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244
Jan ’26
Stumped by URLSession behaviour I don't understand...
I have an app that has been using the following code to down load audio files: if let url = URL(string: episode.fetchPath()) { var request = URLRequest(url: url) request.httpMethod = "get" let task = session.downloadTask(with: request) And then the following completionHandler code: func urlSession(_ session: URLSession, downloadTask: URLSessionDownloadTask, didFinishDownloadingTo location: URL) { try FileManager.default.moveItem(at: location, to: localUrl) In the spirit of modernization, I'm trying to update this code to use async await: var request = URLRequest(url: url) request.httpMethod = "get" let (data, response) = try await URLSession.shared.data(for: request) try data.write(to: localUrl, options: [.atomicWrite, .completeFileProtection]) Both these code paths use the same url value. Both return the same Data blobs (they return the same hash value) Unfortunately the second code path (using await) introduces a problem. When the audio is playing and the iPhone goes to sleep, after 15 seconds, the audio stops. This problem does not occur when running the first code (using the didFinish completion handler) Same data, stored in the same URL, but using different URLSession calls. I would like to use async/await and not have to experience the audio ending after just 15 seconds of the device screen being asleep. any guidance greatly appreciated.
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531
Jan ’26
When updating a VPN app with `includeAllNetworks`, the newer instance of the packet tunnel is not started via on-demand rules
When installing a new version the app while a tunnel is connected, seemingly the old packet tunnel process gets stopped but the new one does not come back up. Reportedly, a path monitor is reporting that the device has no connectivity. Is this the expected behavior? When installing an update from TestFlight or the App store, the packet tunnel instance from the old tunnel is stopped, but, due to the profile being on-demand and incldueAllNetworks, the path monitoring believes the device has no connectivity - so the new app is never downloaded. Is this the expected behavior? During development, the old packet tunnel gets stopped, the new app is installed, but the new packet tunnel is never started. To start it, the user has to toggle the VPN twice from the Settings app. The tunnel could be started from the VPN app too, if we chose to not take the path monitor into account, but then the user still needs to attempt to start the tunnel twice - it only works on the second try. As far as we can tell, the first time around, the packet tunnel never gets started, the app receives an update about NEVPNStatus being set to disconnecting yet NEVPNConnection does not throw. The behavior I was naively expecting was that the packet tunnel process would be stopped only when the new app is fully downloaded and when the update is installed, Are we doing something horribly wrong here?
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635
Jan ’26
use `NEHotspotConfigurationManager.shared.apply(hotspotConfig)` to join a wifi slow on iphone17+
we use the api as NEHotspotConfigurationManager.shared.apply(hotspotConfig) to join a wifi, but we find that in in iphone 17+, some user report the time to join wifi is very slow the full code as let hotspotConfig = NEHotspotConfiguration(ssid: sSSID, passphrase: sPassword, isWEP: false) hotspotConfig.joinOnce = bJoinOnce if #available(iOS 13.0, *) { hotspotConfig.hidden = true } NEHotspotConfigurationManager.shared.apply(hotspotConfig) { [weak self] (error) in guard let self else { return } if let error = error { log.i("connectSSID Error while configuring WiFi: \(error.localizedDescription)") if error.localizedDescription.contains("already associated") { log.i("connectSSID Already connected to this WiFi.") result(["status": 0]) } else { result(["status": 0]) } } else { log.i("connectSSID Successfully connected to WiFi network \(sSSID)") result(["status": 1]) } } Normally it might only take 5-10 seconds, but on the iPhone 17+ it might take 20-30 seconds.
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298
Dec ’25
peer-to-peer networking for iOS, iPadOS, watchOS, tvOS
Our product (rockhawk.ca) uses the Multipeer Connectivity framework for peer-to-peer communication between multiple iOS/iPadOS devices. My understanding is that MC framework communicates via three methods: 1) infrastructure wifi (i.e. multiple iOS/iPadOS devices are connected to the same wifi network), 2) peer-to-peer wifi, or 3) Bluetooth. In my experience, I don't believe I've seen MC use Bluetooth. With wifi turned off on the devices, and Bluetooth turned on, no connection is established. With wifi on and Bluetooth off, MC works and I presume either infrastructure wifi (if available) or peer-to-peer wifi are used. I'm trying to overcome two issues: Over time (since iOS 9.x), the radio transmit strength for MC over peer-to-peer wifi has decreased to the point that range is unacceptable for our use case. We need at least 150 feet range. We would like to extend this support to watchOS and the MC framework is not available. Regarding #1, I'd like to confirm that if infrastructure wifi is available, MC uses it. If infrastructure wifi is not available, MC uses peer-to-peer wifi. If this is true, then we can assure our customers that if infrastructure wifi is available at the venue, then with all devices connected to it, range will be adequate. If infrastructure wifi is not available at the venue, perhaps a mobile wifi router (battery operated) could be set up, devices connected to it, then range would be adequate. We are about to test this. Reasonable? Can we be assured that if infrastructure wifi is available, MC uses it? Regarding #2, given we are targeting minimum watchOS 7.0, would the available networking APIs and frameworks be adequate to implement our own equivalent of the MC framework so our app on iOS/iPadOS and watchOS devices could communicate? How much work? Where would I start? I'm new to implementing networking but experienced in using the MC framework. I'm assuming that I would write the networking code to use infrastructure wifi to achieve acceptable range. Many thanks! Tim
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0
1.7k
Sep ’25
iOS 18; Can no longer connect app to camera over Ad Hoc insecure network
We have an old iOS app and an old camera that connects using Wi-Fi either using an access point or Ad Hoc network, e.g., iPhone/iPad connects to the camera's Wi-Fi directly... How it works (old legacy app/system, which cannot be redesigned): Camera is configured to Ad Hoc Wi-Fi network (insecure TCP). iPhone connects to this insecure Wi-Fi. Camera uses Bonjour service to broadcast its IP address. App reads in IP address and begin to send messages to the camera using NSMutableURLRequest, etc. All this works fine for iOS 17. But in iOS 18 step 4 stopped working. App simply doesn't get any responses! We believe we have configured ATS properly (App Store version): In panic we have also tried this in Test Flight version: The latter actually seemed to make a difference when running the app on macOS Apple Silicon. But on iOS it didn't seem to make any difference. Occasionally, I was lucky to get connection on on iPhone 16 Pro with iOS 18. But for the 'many' iPads I have tried I couldn't. I also tried to install CFNetwork profile and look at the logs but I believe I just got timeout on the requests. Questions: Why it iOS 18 different? Bonjour works fine, but NSSURLRequests doesn't Do we configure ATS correctly for this scenario? What should I look for in the Console log when CFNetwork profile is installed? Should I file a TSI? Thanks! :)
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206
May ’25
Boost ***** 1.86.0 on iOS 18.3.1 connection times out
We use Boost ***** (1.86.0) for WebSockets in an iOS application using a self-signed certificate. The ***** WebSocket client works fine on iOS 18.1 and every other OS (Windows, Android, Linux, etc...) but not iOS 18.3.1 and possibly versions before 18.3.1 but later than iOS 18.1. Has anyone else ran into this issue and how did you resolve? What could have changed after iOS 18.1 that would prevent a WSS Websocket from connecting that works fine on iOS 18.1?
7
0
358
Mar ’25