Per the request above, opened FB11869808. Thanks a lot!

Adding to the above: as an interim workaround: is there any way to get a positive, deterministic indication that a utun interface has been created by nesessionmanager BEFORE we try to send the IPC request to the extension? It seems that as "roee84" mentioned above, if the IPC registration is delayed a bit, until a utun is created, all is fine. If, on the other hand, we send an IPC registration request as soon as we recieve "Connecting" state, then it indeed results in two utuns being created (while only one is actually used).

Is the above true for macOS/iOS 26? Is it still Apple's decision not to comply with RFC 9147, at least in terms of custom extensions support? Thanks.