Hello, I am working to integrate the new com.apple.developer.networking.carrier-constrained.app-optimized entitlement in my iOS 26 app so that my app can use a carrier-provided satellite network, and want to confirm my understanding of how to detect and optimize for satellite network conditions. (Ref: https://developer.apple.com/documentation/bundleresources/entitlements/com.apple.developer.networking.carrier-constrained.app-optimized ) My current approach: I plan to set the entitlement to true once my app is optimized for satellite networks. To detect if the device is connected to a satellite network, I intend to use the Network framework’s NWPath properties: isUltraConstrained — I understand this should be set to true when the device is connected to a satellite network. (Ref: https://developer.apple.com/documentation/network/nwpath/isultraconstrained ) linkQuality == .minimal — I believe this will also be set in satellite scenarios, though it may not be exclusive to satellite connections. (Ref: https://developer.apple.com/documentation/network/nwpath/linkquality-swift.enum/minimal ) Questions: Is it correct that isUltraConstrained will reliably indicate a satellite connection? Should I also check for linkQuality == .minimal, or is isUltraConstrained sufficient? Are there any additional APIs or best practices for detecting and optimizing for satellite connectivity that I should be aware of? Thank you for confirming whether my understanding and approach are correct, and for any additional guidance.

Recently, my application was having trouble connecting socket using TCP protocol after it was reinstalled. The cause of the problem was initially that I did not grant local network permissions when I reinstalled, I was aware of the problem, so socket connect interface worked fine after I granted permissions. However, the next time I repeat the previous operation, I also do not grant local network permissions, and then turn it back on in the Settings, and socket connect interfcae does not work properly (connect interface return errno 65, the system version and code have not changed). Fortunately, socket connect success after rebooting the phone, and more importantly, I was able to repeat the problem many times. So I want to know if the process between when I re-uninstall the app and deny local network permissions, and when I turn it back on in Settings, is that permissions have been granted normally, and not fake, and not required a reboot to reset something for socket coonnect to take effect.

Hi, I am trying to update an old prototype I made for tvOS using DNSServiceBrowse(). The target was tvOS 17. My old build from September 2023 still works fine: It can discover computers on the same local network as the Apple TV (simulator). However, now that I am using Xcode 16, the DNSServiceBrowse() callback (of type DNSServiceBrowseReply) receives the error code: -65570. The call to DNSServiceBrowse() itself returns no error, neither does the following call to DNSServiceProcessResult() — which actually triggers the call of the callback. I found nowhere in the Internet any list of possible error codes received by the callback, so I have no idea what it means. So, my first question is: What does this error code mean? (And is there any list of the possible errors somewehere, with their meaning?) Since it was a prototype, I have no provisioning profile defined for it. Could that be related to the issue? Since I will make a real app out that prototype (targeting tvOS 18), I will have to define a provisioning profile for it. Would a provisioning profile for the app solve the issue? If yes, are there any requirements for that profile that I should take into account to solve the issue? Thank you in advance for any help, Marc

I'm trying to use NEHotspotNetwork to configure an IoT. I've read all the issues that have plagued other developers when using this framework, and I was under the impression that bugs were filed and fixed. Here are my issues in hopes that someone can catch my bug, or has finally figured this out and it's not a bug in the framework with no immediate fix on the horizon. If I use the following code: let config = NEHotspotConfiguration(ssid: ssid) config.joinOnce = true KiniStatusBanner.shared.show(text: "Connecting to Kini", in: presentingVC.view) NEHotspotConfigurationManager.shared.apply(config) { error in DispatchQueue.main.async { if let nsError = error as NSError?, nsError.domain == NEHotspotConfigurationErrorDomain, nsError.code == NEHotspotConfigurationError.alreadyAssociated.rawValue { print("Already connected to \(self.ssid)") KiniStatusBanner.shared.dismiss() self.presentCaptivePortal(from: presentingVC, activationCode: activationCode) } else if let error = error { // This doesn't happen print("❌ Failed to connect: \(error.localizedDescription)") KiniStatusBanner.shared.update(text: "Failed to Connect to Kini. Try again later.") KiniStatusBanner.shared.dismiss(after: 2.5) } else { // !!!! Most often, this is the path the code takes NEHotspotNetwork.fetchCurrent { current in if let ssid = current?.ssid, ssid == self.ssid { log("✅✅ 1st attempt: connected to \(self.ssid)") KiniStatusBanner.shared.dismiss() self.presentCaptivePortal(from: presentingVC, activationCode: activationCode) } else { // Dev forums talked about giving things a bit of time to settle and then try again DispatchQueue.main.asyncAfter(deadline: .now() + 2) { NEHotspotNetwork.fetchCurrent { current in if let ssid = current?.ssid, ssid == self.ssid { log("✅✅✅ 2nd attempt: connected to \(self.ssid)") KiniStatusBanner.shared.dismiss() self.presentCaptivePortal(from: presentingVC, activationCode: activationCode) } else { log("❌❌❌ 2nd attempt: Failed to connect: \(self.ssid)") KiniStatusBanner.shared.update(text: "Could not join Kini network. Try again.") KiniStatusBanner.shared.dismiss(after: 2.5) self.cleanupHotspot() DispatchQueue.main.asyncAfter(deadline: .now() + 2) { print("cleanup again") self.cleanupHotspot() } } } } log("❌❌ 1st attempt: Failed to connect: \(self.ssid)") KiniStatusBanner.shared.update(text: "Could not join Kini network. Try again.") KiniStatusBanner.shared.dismiss(after: 2.5) self.cleanupHotspot() } As you can see, one can't just use NEHotspotConfigurationManager.shared.apply and has to double-check to make sure that it actually succeeds, by checking to see if the SSID desired, matches the one that the device is using. Ok, but about 50% of the time, the call to NEHotspotNetwork.fetchCurrent gives me this error: NEHotspotNetwork nehelper sent invalid result code [1] for Wi-Fi information request Well, there is a workaround for that randomness too. At some point before calling this code, one can: let locationManager = CLLocationManager() locationManager.requestWhenInUseAuthorization() That eliminates the NEHotspotNetwork nehelper sent invalid result code [1] for Wi-Fi information request BUT... three issues. The user is presented with an authorization alert: Allow "Kini" to use your location? This app needs access to you Wi-Fi name to connect to your Kini device. Along with a map with a location pin on it. This gives my users a completely wrong impression, especially for a device/app where we promise users not to track their location. They actually see a map with their location pinned on it, implying something that would freak out anyone who was expecting no tracking. I understand why an authorization is normally required, but since all we are getting is our own IoT's SSID, there should be no need for an authorization for this, and no map associated with the request. Again, they are accessing my IoT's network, NOT their home/location Wi-Fi SSID. My app already knows and specifies that network, and all I am trying to do is to work around a bug that makes it look like I have a successful return from NEHotspotConfigurationManager.shared.apply() when in fact the network I was looking for wasn't even on. Not only do I get instances where the network doesn't connect, and result codes show no errors, but I also get instances where I get an alert that says that the network is unreachable, yet my IoT shows that the app is connected to its Wi-Fi. On the iOS device, I go to the Wi-Fi settings, and see that I am on the IoT's network. So basically, sometimes I connect, but the frameworks says that there is no connection, and sometimes it reports a connection when there is none. As you can see in the code, I call cleanupHotspot() to make the iOS device get off of my temp Wi-Fi SSID. This is the code: func cleanupHotspot() { NEHotspotConfigurationManager.shared.removeConfiguration(forSSID: ssid) } That code gets called by the above code when things aren't as I expect and need to cleanup. And I also call it when the user dismisses the viewcontroller that is attempting to make the connection. It doesn't always work. I get stuck on the tempo SSID, unless I go through this whole thing again: try to make the connection again, this time it succeeds quickly, and then I can disconnect. Any ideas? I'm on iOS18.5, and have tried this on multiple iPhones including 11, 13 and 16.

Simulator: iPhone 16 pro (iOS 26) Minimum Deployments: iOS 16.0+, not iOS 17. Here is the demo: import SwiftUI import NetworkExtension struct ContentView: View { private var monitor = NWPathMonitor() var body: some View { VStack { Text("Hello, world!") } .task { let _ = URLSession.shared } } }

I'm working on a project that says it's to be based on the QNE2TransparentProxyMac sample code but don't have the original sample code. Can I get a pointer to the sample code and documentation please? Google search didn't find it for some reason. Thanks! Peter

We have a transparent proxy in a system extension. We intercept all traffic from machine using 0.0.0.0 and :: as include rules for protocol ANY. We intercept all DNS queries and forward them to a public or private DNS server based on whether its a private domain or not. In most cases, everything works fine. However, sometimes, git command (over SSH) in terminal fail to resolve DNS and receives below error: ssh: Could not resolve hostname gitserver.corp.company.com: nodename nor servname provided, or not known While investigating, we found that mDNSResponder was using HTTPS to dns.google to resolve the queries securely. DNS Request logs While this works for public domains (not how we would want by anyways), the query fails for our company private domains because Transparent Proxy cannot read the DNS query to be able to tunnel or respond to it. Several years back when secure DNS was introduced to Apple platforms, I remember in one of the WWDC sessions, it was mentioned that VPN providers will still get plain text queries even when system has secure DNS configured or available. In this case, there is no DNS proxy or any other setting to enable secure DNS on the machine except for Google public DNS configured as DNS server. So my question is: Shouldn't transparent proxy also get plain text DNS queries like PacketTunnelProvider? And is there a way to disable/block the secure DNS feature in mDNSResponder or on machine itself? Using Transparent proxy or MDM or any other config? So that transparent proxy can handle/resolve public and private domains correctly. Another thing we noticed that not all queries are going over secure channel. We still get quite a few queries over plain UDP. So is there any rule/criteria when mDNSResponder uses secure DNS and when plain text DNS over UDP?

Hi all, I’m developing a companion iOS app that connects to a device-created Wi-Fi hotspot to transfer videos or other files WebSocket. The challenge is: once the iPhone connects to this hotspot, it loses internet access because iOS routes all traffic through Wi-Fi. However, I’d like to keep the iPhone’s cellular data active and usable while staying connected to the local hotspot — so the app can access cloud APIs, or the user can continue using other apps that require internet access. I understand that iOS prioritizes Wi-Fi over cellular, but are there any supported workarounds or patterns (e.g., MFi programs, local-only Wi-Fi access, NEHotspotConfiguration behavior, etc.) that : • Using Wi-Fi only for local communication; • cellular to remain active for internet access. Any insights or Apple-recommended best practices would be greatly appreciated — especially any official references regarding MFi Accessory setup or NEHotspotConfiguration behavior in this context. Thanks in !

I tried to test out the new Wi-Fi aware framework but encountered the issue in the title. My operation steps are as follows: 1) create a hello world project using Xcode 26.0 beta 2) add Wi-Fi Aware entitlement and service following the sample code in "Building peer-to-peer apps" 3) run my code on an iPhone 16 Pro and fail at the building stage. The error message is "Provisioning profile "iOS Team Provisioning Profile: [my project name]" doesn't include the com.apple.developer.wifi-aware entitlement." I also tried to build the sample app but faced the same issue.

Just tried to re-run the code below (previously discussed https://developer.apple.com/forums/thread/747815) and filed as bug: https://feedbackassistant.apple.com/feedback/13678278 Still broken on macOS 26 first beta. Any chance anything can be done about this @eskimo? thanks, Martin import Foundation import Network let localPort: NWEndpoint.Port = 12345 var connections: [NWConnection] = [] func startFlow(remotePort: UInt16) { let params = NWParameters.udp params.allowLocalEndpointReuse = true params.requiredLocalEndpoint = NWEndpoint.hostPort(host: "0.0.0.0", port: localPort) let conn = NWConnection(host: "93.184.216.34", port: .init(rawValue: remotePort)!, using: params) conn.stateUpdateHandler = { newState in print("connection \(remotePort) did change state, new: \(newState)") } conn.start(queue: .main) connections.append(conn) } func main() { startFlow(remotePort: 23456) startFlow(remotePort: 23457) dispatchMain() } main()

Hello, I’m developing an iOS app with Xcode (Objective-C / Swift), and I would like to know if there is any supported way to retrieve a list of nearby Wi-Fi networks (their SSID and signal strength). I know that NEHotspotConfigurationManager allows to configure a specific network, and the Access WiFi Information entitlement allows getting the current connected network. But is there any API (public, private, or special entitlement) that allows scanning nearby Wi-Fi networks — even for limited purposes like configuration of IoT equipment, or MFi devices? I have seen some apps doing this in the past (probably via private API), but I want to know what is the current official solution. Thanks a lot!

Hello! I develop transparent proxy based application, and I'm receiving a lot of crash reports from macOS 15.5 for crash in __88-[NEExtensionAppProxyProviderContext setInitialFlowDivertControlSocket:extraValidation:]_block_invoke.90 when stopping. Even very old versions of my software started crashing on macOS 15.5. I checked my extension that it correctly calls setTunnelNetworkSettings:nil on proxy stop, but crash is still here. Does anybody else have this problem? Do you know any workaround for it?

Our application has initiated an NSURLSession data task, and we have received an initiation ID. However, Application not received callback on the subsequent activity: the task has not been requested, has not timed out, and no error callback has been received. [06/17 09:29:40:559][ 0x282a7d8c0] Requested TaskIdentifier 120 2025-06-17 09:29:40.623337 +0530 nsurlsessiond SUBMITTING: com.apple.CFNetwork-cc-166-373-Task .<120>:A71666 default 2025-06-17 09:29:40.631280 +0530 dasd Submitted Activity: com.apple.CFNetwork-cc-166-373-Task .<120>:A71666 at priority 10 default Seen couple of rejection with for CPUUsagePolicy and MemoryPressurePolicy 2025-06-17 09:29:40.989360 +0530 dasd com.apple.CFNetwork-cc-166-373-Task .<120>:A71666:[ {name: CPUUsagePolicy, policyWeight: 5.000, response: {Decision: Must Not Proceed, Score: 0.00, Rationale: [{[Max allowed CPU Usage level]: Required:90.00, Observed:95.00},]}} {name: MemoryPressurePolicy, policyWeight: 5.000, response: {Decision: Must Not Proceed, Score: 0.00, Rationale: [{[memoryPressure]: Required:1.00, Observed:2.00},]}} ], FinalDecision: Must Not Proceed} default 2025-06-17 10:55:22.500277 +0530 dasd com.apple.CFNetwork-cc-166-373-Task .<120>:A71666:[ {name: MemoryPressurePolicy, policyWeight: 5.000, response: {Decision: Must Not Proceed, Score: 0.00, Rationale: [{[memoryPressure]: Required:1.00, Observed:2.00},]}} ], FinalDecision: Must Not Proceed} default And more an hour later then it throws with an error BUT NEVER indicated the same to client 2025-06-17 10:55:27.426549 +0530 WAVE PTX Task .<120> is for <>.<>.<120> default 2025-06-17 10:55:27.776951 +0530 nsurlsessiond Task .<120> summary for task failure {transaction_duration_ms=5147145, response_status=-1, connection=0, reused=1, request_start_ms=0, request_duration_ms=0, response_start_ms=0, response_duration_ms=0, request_bytes=0, response_bytes=0, cache_hit=false} default 2025-06-17 10:55:27.777096 +0530 nsurlsessiond NDSession <714296D7-20F9-4A0A-8C31-71FB67F39A56> Task .<120> for client will be retried after error Error Domain=_nsurlsessiondErrorDomain Code=6 UserInfo={NSErrorFailingURLStringKey=, NSErrorFailingURLKey=, _NSURLErrorRelatedURLSessionTaskErrorKey=, _NSURLErrorFailingURLSessionTaskErrorKey=} - code: 6 default Then It got resumed and says successful but never got any callback on the same to client 2025-06-17 10:55:28.877245 +0530 nsurlsessiond NDSession <714296D7-20F9-4A0A-8C31-71FB67F39A56> Task .<120> resuming default 2025-06-17 10:55:55.225456 +0530 nsurlsessiond Task .<120> received response, status 401 content K default 2025-06-17 10:55:55.250371 +0530 nsurlsessiond Task .<120> finished successfully default Please refer feedback for diagnose logs: https://feedbackassistant.apple.com/feedback/18173303

Hi guys, I try to create a content filter app by using network extension api. When it comes to a https/tls remote endpoint, the remoteEndpoint.hostname will always be "" instead of the actual hostname. How can I extract the actual hostname? private func filterTraffic(flow: NEFilterSocketFlow) -> NEFilterNewFlowVerdict { // Default action from settings will be used if no rules match logger.error("filter traffic...") guard let remoteEndpoint = flow.remoteEndpoint as? NWHostEndpoint else { logger.error("not a NWHostEndpoint)") return .allow() } logger.error("host name: \(remoteEndpoint.hostname)") if remoteEndpoint.hostname.hasSuffix("google.com"){ logger.error("google.com") return .drop() } return .allow() } code-block

Hi all. Title says it all really. I have an app on MacOS that sends multicast UDP to multiple iOS devices. It shows realtime bar numbers of music played back by a playback software. It was all working until I tried a direct ethernet connection between Mac and phone - a scenario that would be quite common in the theatre world where machines dont have internet connection and people dont rely on wifi. How can I choose which interface my app sends the data through? Here is my connection function: func openConnection() { let params = NWParameters.udp params.allowLocalEndpointReuse = true params.includePeerToPeer = true let endpoint = NWEndpoint.hostPort(host: host, port: port) let conn = NWConnection(to: endpoint, using: params) self.connection = conn conn.stateUpdateHandler = { state in switch state { case .ready: print("Multicast connection ready to \(self.host)") UDPClient.console.log("Multicast connection ready to \(self.host)") case .failed(let error): print("Multicast connection failed: \(error)") default: break } } let udpQueue = DispatchQueue(label: "UDPClientQueue") conn.start(queue: udpQueue) } Thanks for any help in advance!

I'm using Network framework for communication between devices. The first time I instantiate an NWBrowser, it will prompt the user with a popup that says: Allow <app name> to find devices on local networks? The problem is, once I upgraded from Xcode 15.4 to Xcode 16.4, the popup doesn't appear; it says in the debug window: nw_browser_fail_on_dns_error_locked [B1] nw_browser_dns_service_browse_callback failed: PolicyDenied(18,446,744,073,709,486,046) I do have the info.plist keys Privacy-Local Network Usage Description (NSLocalNetworkUsageDescription) and Bonjour Services (NSBonjourServices) so it's not that. Also, It still works on a real device. I think something changed with Xcode 16 that tightened the security on a simulator, or maybe disabled Network framework entirely. It's not the firewall on my computer because that is turned off. I'm using an M1 MacBook Pro.

This is probably a basic question but I wanted to ask your advice for the best way to take consenting users' Watch data from Apple Health Kit and send it to our central server? One idea we had was to create an iOS app that gets the data from Apple's Health SDK on the phone and sends it to our server. Would appreciate any help here, thank you.

I implemented a Network Extension in the macOS, use NETransparentProxyProvider. After installing and enabling it, I implemented a UDP client to test its. I found that the UDP client failed to send the data successfully (via sendto, and it returned a success), and when using Wireshark to capture the network data packet, I still couldn't see this UDP data packet. The code for Network Extension is like this: @interface MyTransparentProxyProvider : NETransparentProxyProvider @end @implementation MyTransparentProxyProvider - (void)startProxyWithOptions:(NSDictionary *)options completionHandler:(void (^)(NSError *))completionHandler { NETransparentProxyNetworkSettings *objSettings = [[NETransparentProxyNetworkSettings alloc] initWithTunnelRemoteAddress:@"127.0.0.1"]; // included rules NENetworkRule *objIncludedNetworkRule = [[NENetworkRule alloc] initWithRemoteNetwork:nil remotePrefix:0 localNetwork:nil localPrefix:0 protocol:NENetworkRuleProtocolAny direction:NETrafficDirectionOutbound]; NSMutableArray<NENetworkRule *> *arrIncludedNetworkRules = [NSMutableArray array]; [arrIncludedNetworkRules addObject:objIncludedNetworkRule]; objSettings.includedNetworkRules = arrIncludedNetworkRules; // apply [self setTunnelNetworkSettings:objSettings completionHandler: ^(NSError * _Nullable error) { // TODO } ]; if (completionHandler != nil) completionHandler(nil); } - (BOOL)handleNewFlow:(NEAppProxyFlow *)flow { if (flow == nil) return NO; char szProcPath[PROC_PIDPATHINFO_MAXSIZE] = {0}; audit_token_t *lpAuditToken = (audit_token_t*)flow.metaData.sourceAppAuditToken.bytes; if (lpAuditToken != NULL) { proc_pidpath_audittoken(lpAuditToken, szProcPath, sizeof(szProcPath)); } if ([flow isKindOfClass:[NEAppProxyTCPFlow class]]) { NWHostEndpoint *objRemoteEndpoint = (NWHostEndpoint *)((NEAppProxyTCPFlow *)flow).remoteEndpoint; LOG("-MyTransparentProxyProvider handleNewFlow:] TCP flow! Process: (%d)%s, %s Remote: %s:%s, %s", lpAuditToken != NULL ? audit_token_to_pid(*lpAuditToken) : -1, flow.metaData.sourceAppSigningIdentifier != nil ? [flow.metaData.sourceAppSigningIdentifier UTF8String] : "", szProcPath, objRemoteEndpoint != nil ? (objRemoteEndpoint.hostname != nil ? [objRemoteEndpoint.hostname UTF8String] : "") : "", objRemoteEndpoint != nil ? (objRemoteEndpoint.port != nil ? [objRemoteEndpoint.port UTF8String] : "") : "", ((NEAppProxyTCPFlow *)flow).remoteHostname != nil ? [((NEAppProxyTCPFlow *)flow).remoteHostname UTF8String] : "" ); } else if ([flow isKindOfClass:[NEAppProxyUDPFlow class]]) { NSString *strLocalEndpoint = [NSString stringWithFormat:@"%@", ((NEAppProxyUDPFlow *)flow).localEndpoint]; LOG("-[MyTransparentProxyProvider handleNewFlow:] UDP flow! Process: (%d)%s, %s LocalEndpoint: %s", lpAuditToken != NULL ? audit_token_to_pid(*lpAuditToken) : -1, flow.metaData.sourceAppSigningIdentifier != nil ? [flow.metaData.sourceAppSigningIdentifier UTF8String] : "", szProcPath, strLocalEndpoint != nil ? [strLocalEndpoint UTF8String] : "" ); } else { LOG("-[MyTransparentProxyProvider handleNewFlow:] Unknown flow! Process: (%d)%s, %s", lpAuditToken != NULL ? audit_token_to_pid(*lpAuditToken) : -1, flow.metaData.sourceAppSigningIdentifier != nil ? [flow.metaData.sourceAppSigningIdentifier UTF8String] : "", szProcPath ); } return NO; } @end The following methods can all enable UDP data packets to be successfully sent to the UDP server: 1.In -[MyTransparentProxyProvider startProxyWithOptions:completionHandler:], add the exclusion rule "The IP and port of the UDP server, the protocol is UDP"; 2.In -[MyTransparentProxyProvider startProxyWithOptions:completionHandler:], add the exclusion rule "All IPs and ports, protocol is UDP"; 3.In -[MyTransparentProxyProvider handleNewFlow:] or -[MyTransparentProxyProvider handleNewUDPFlow:initialRemoteEndpoint:], process the UDP Flow and return YES. Did I do anything wrong?

Hi all, im trying to implement a per-app vpn in my network extension (packet tunnel with custom protocol), where only the traffic generated by my application should be routed trought my network extension. It is possible to accomplish that on a non managed or supervised device? Setting the routingMethod as .sourceApplication in NEPacketTunnelProvider is not possible as it is read-only, can it work trying overriding the var as a computed property? The documentation lack of examples. Thanks in advance! Love

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?