https://bugs.winehq.org/show_bug.cgi?id=53499
--- Comment #11 from Hans Leidekker hans@meelstraat.net --- (In reply to Stanislav Slow from comment #10)
(In reply to Hans Leidekker from comment #7)
You should try to figure out where this ID comes from. Is it a MAC address? In that case I would expect an all-zero ID if for the loopback address. Perhaps a +relay trace will tell us more.
Are there any specific keywords I could grep from log to prove or disprove the theory?
Following your theory about client IDs you could try to capture network packets from the game running on Windows and identify this ID. Then grep for strings with same format, or stuff surrounding it.
More generally comparing packets from clients running on Windows and Wine and see where they diverge may a good approach.