L4D 2 server IP: 92.48.112.222:27016
Mumble server: details will follow

If you want to use it the lobby leader should use the console command sv_search key xxx (replace xxx with the key provided by Atilla or me - please keep it to yourselves/within the group) before creating the lobby.
Alternatively you can use the command mm_dedicated_force_servers 92.48.112.222:27016



Public players shouldn't be able to randomly connect via lobbies, however they should be able to join a lobby or a running game.
So you'll always find an empty server to play on :D

I will do some tweaking and stuff during the next days/weeks so expect some downtime and possibly problems with the server.