We it is also on my game. I produced a normal multiplayer session setup and ping is 9999 but I can connect normaly to session.
Btw:
You said reproducible test… Setup a normal find sessions example with a widget that you add to child.
You need to test this with a other computer that is not in local network… but even if it has in local network a ping of 9999 without any firewalls or anti virus or something else.
Cheers.