This hotfix is meant to fix a room browser bug that would delete rooms after a while. This should never happen again.
I'm sorry for the inconvenience.
There are some players that aren't being able to join or being joined by others. Please try the following:
1- Make sure you execute the OpenPortTool outside the game. It will propose you to launch the game after but don't launch. Launch always from steam. (When possible)
2- Make sure your firewall isn't blocking the game.
3- If this isn't working it may be because the room browser uses external (or public) IP addresses and you are trying to connect to a local (LAN) room. If this is the case, please try using the local IP address that should be something like 192.168.x.x.
Hope it helps.
Thank you for playing.