I asked about this in the V-Rising Discord, server channel, but didn't find resolution.
It now supports LAN play, which should let me go offline in steam, then connect to the server (running on the same machine).
I added -lan to the commandline, restarted, then tried to connect. All IP addresses (127.0.0.0, 0.0.0.0, <external ip>, docker IP address, etc all fail to connect (I went through and tried with and without the client lan button pushed combined with adding the port or not in all combinations, the one that works without the -lan option connects, then gets to 5/5 then gets a connection timed out error.)
Without the -lan option I can connect, but if I'm offline in steam it plays from 3-10 minutes then I get a communication error (I think the authentication finally fails) and I get booted.
The response on the official discord is, Linux isn't supported...which is expected, but not as helpful as I had hoped.
I'm running with the default commandlines shown in the github page, I did tweak the server to make it PVE and a couple settings, nothing with the network.
Thanks for any suggestions.
This is my first time using Docker, I'm on Ubuntu 22.10 with latest patches applied.