At the github theres a bit of instruction.
Mod uses 30502 port. So that port needs to forwarded on your router and in your firewalls for direct connect to work.
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https://github.com/Zetrith/Multiplayer/wiki/Hosting-and-joiningMod uses 30502 port. So that port needs to forwarded on your router and in your firewalls for direct connect to work.