We've been using network framework for peer to peer connectivity since iOS 15. Since the introduction of iOS 17 we've been getting the following for our NWListener when attempting to establish a connection with any multipathServiceType enabled. We're not doing anything special here. On iOS 17.x devices (we've tested 17.1, 17.2, 17.4) we simply enable multipath services by adding the multipath capability and then setting multipathServiceType to .handover or .interactive on our NWParameters. The devices never connect when we try establish an NWConnection. This works on all non-iOS 17.x devices. This is reproducible using the Apple Peer-to-Peer NWConnection TicTacToe sample code.

We have a relatively simple app that using Network.Framework, NWConnection, NWEndpoint to setup TCP connections with nearby devices also using the app. It's actually been working great for a while now but we've recently noticed with iOS 17.4/17.4.1 that we're spontaneously getting: nw_proto_tcp_route_init [C6:3] no mtu received sometimes the [C6:3] will be [C7:3] or another similar code. We may also occasionally see No route to Host appear in our console logs though this isn't definite. After this point the connection is effectively lost but we don't actually receive any updates on our NWConnection stateUpdateHandler to action on. It's sort of dead in the water so to speak. We've reproduced this issue with multiple devices on iOS 17.4.x and in multiple network settings (in office, cafe, home networks...etc). Nothing seems to make a difference. Any ideas on how to fix or workaround this? I saw a similar issue here: https://developer.apple.com/forums/thread/669519 but the original author never followed up and it's around 3 years old. I've captured a sysdiagnose log and can submit an issue if it warrants filing a bug report.