Any update or solution for this. I am also trying the same

I am trying to concurrently direct traffic out through either wifi or cellular within Packet Tunnel Provider

I took a look at NEIPv4Settings. It seems for configuring the TUN interface. How can I create two NWUDPSessions, one over Wi-Fi, and the other over Cellular ? I wonder what APIs are used in this VPN app (https://apps.apple.com/us/app/speedify/id999025824#?platform=iphone) for sending traffic over both Wi-Fi and Cellular simultaneously.

Below is a related post (https://developer.apple.com/forums/thread/76711), and I am looking for the solution to the exact same problem. ////////////////////////////////////////////////////////////////// I too am trying to concurrently direct traffic out through either wifi or cellular (based on some policies/business logic similar to the OP) but running into problems. The approaches described here (and similar others here and here) to bind a BSD socket to cellular - via bind(ip of cellular) or setsockopt(IP_BOUND_IF, cellular i/f) - work great when performed within an app but do not work when performed from within my Packet Tunnel provider. The binding itself succeeds, but then any attempts to connect on the cellular-bound socket always fail with EADDRNOTAVAIL. I ran some additional experiments and found: The connect works perfectly fine when done from an app (instead of within my PT provider). I also tried this as a separate app while my PT provider was actively running at the same time and had no problems. I can connect() on the cellular-bound socket from within my packet tunnel provider as long as it is before I call the startTunnel completion handler (i.e. before VPN tunnel is brought up by the system). IOW, the only time the connect() fails is when I try to do it from within my PT provider and only after my tunnel is started (after I call the completion handler). The same EADDRNOTAVAIL occurs with both TCP and UDP sockets. The EADDRNOTAVAIL doesn't seem to be related to the port already being used (which is the typical cause), since I'm calling bind() with 0 for the port. So, I'm wondering: Am I doing something wrong, i.e. is there something subtlely different that needs to be done within a PT provider that isn't typically required in an app? Is there a known issue with connecting cellular-bound sockets from within a tunnel provider? Is there some other method I can use to send some subset of my traffic over cellular, while still concurrently sending most of my traffic over wifi? I'm running a single full tunnel (not split) and finding that createTCPConnectionToEndpoint only allows me to send out over the current default network (not selectively and concurrently out either cellular or wifi when both are available). Any help would be greatly appreciated. Thanks!