The "different from server" message is a security and stability check. If the server is running but your client has an older (or newer) version of the v2.ff file, the game disconnects you to prevent crashes or desync issues. Corrupt Installations
files on your client and those on the game server you are trying to join . This specifically refers to the fastfile (
If players are frequently getting this error on your server, ensure your server files are correctly synced: Verify FastDL