I had to take the online server down because the game hasn't even been close to covering multiplayer server costs for years now - and apparently causing the game to crash on startup when the DNS record expired.
The game now has a Server.exe included with it, which can be used to run your own matchmaking server - just point the online bit in settings.cfg to point to the ip address of where you've hosted it, and open port 3261.
Sorry for the hassles here.