This tends to occur when you're joining a LAN server using its external IP address (the one from your ISP).Solution One
- Go to the server list screen
- hit insert
- Enter the servers LAN IP Address (and port if needed), and hit enter.
- Join the server that appears with the LAN address.
- Open your console (~ [tilde] key)
- type joinGame("xxx.xxx.xxx.xxx"); (replace the Xs with your Servers IP.
- Hit enter
If this occurs while connecting to a non-local server