G'day again Rat Racers.
Regarding the earlier server maintenance, public matchmaking lobbies should be stable, however, you may find yourself unable to join Private Lobbies entirely even with a correct lobby code.
This is due to a bug with lobby code validation that was only caught after deployment during an unrelated playtest for a future bug bash patch. This bug has now been fixed, however currently I'm experiencing a power outage and cannot yet update the public matchmaking server nor the game itself at this time. I apologise for the inconvenience.
In the meantime, a workaround for the technically minded is to deploy your own instance of the Matchmaking server software (visible in Tools in your Steam Library) and use that as a private lobby instance via it's own "Enter Matchmaking" mode:
If it's a matchmaking server instance on LAN, all you need to know is the server machine's IP address. However, if it's a server meant to be exposed to the internet, you'll need to open Port 19777 on your router for your server for it to be reachable by your friends. They'll also need to know your internet connections public IP address. For more information, please consult the game's manual, located in the game's data folder.
Generally, just installing and launching the GUI server before launching the game should be enough. If you're running the matchmaking server on the same PC you're playing Rattus Velocitas on, connecting to localhost (127.0.0.1) on your end should work.
In addition, some other issues affecting the live patch were found:
If your system time is set incorrectly, you may find the game softlocks when "RAT RACE START!" appears. To workaround this issue, please ensure you have network time synchronisation enabled in your Operating System. A fix has already been made for this bug and will be deployed with the server update as soon as possible.
If the connection to the matchmaking server is lost mid-race, the lobby screen will be corrupted upon returning from the race. Only workaround is relaunching the game here; sorry about that. :(
Currently, the performance ratio calculation may be slightly affected by network race time synchronisation delay; in the majority of cases this should be harmless.
The Tuesday bug bash patch should still release around October 28 @ 12PM AEST with fixes for all these issues. Provided power is restored in time, the lobby codes bug in particular should be fixed by October 27 2025 @ 10:30PM AEST on the current live patch, will keep the community updated.