What to do if you can't find a room ID — School Labyrinth Steam update #911015
If you cannot find a room after searching for an ID in multiplayer, the player you are playing with may have a different Steam download region setting...
If you cannot find a room after searching for an ID in multiplayer, the player you are playing with may have a different Steam download region setting. Go to Steam->Settings->Downloads->Download Region and try adjusting the settings accordingly.