Left 4 Dead 2 lobby will not use my server

The classic Left 4 Dead 2 problem is a group that starts a lobby and lands on an official server. Here is why, and what else to check.

1. Everyone needs the same search key

1. Set sv_search_key ourgroup in left4dead2/cfg/server.cfg and restart the server.
2. Every player runs sv_search_key ourgroup in their own console before making the lobby.
3. The lobby leader then starts the campaign, and matchmaking sends the group to the server with that key.
4. Afterwards, players clear it with sv_search_key "", or public matchmaking will find them nothing.

2. Check the lobby settings

• The lobby's game mode has to be one of the modes in sv_gametypes on your server.
• The lobby difficulty and campaign must be ones your server can run.
• sv_allow_lobby_connect_from_steam must be 1 on the server.

3. Direct connect always works

If the lobby refuses to cooperate, everyone can run connect IP:Port in the console instead. That bypasses matchmaking completely. It is the quickest way to prove the server itself is healthy.

4. The server is not in the browser

• sv_lan must be 0.
• Clear the browser filters for full and password protected servers.
• Add the server to Steam favourites once you find it.

5. Players join and sit as spectators

That is sv_maxplayers raised above four in co-op without a plugin to hand out characters. Either lower it back or install the plugin the mode needs.

6. The server crashes on a custom campaign

• Check the .vpk file is directly in left4dead2/addons.
• Read the console for the missing map or file it names.
• Remove the last campaign you added and restart to confirm.

Open a ticket from Support in the Client Area with the last 50 lines of console output if none of this fits.