CSGO: "Reject Connect From Lobby"

Have you encountered the issue with an error saying “You may only connect to this server from a lobby”? Or the error message “#Valve_Reject_Connect_From_Lobby” in the console?

This is most likely a client-sided issue and usually because you were still connected to a server in-game and then tried to connect to your DatHost server. You must always be in the game lobby when connecting to the server.

Solution: Disconnect from the server you are connected to before connecting to your DatHost server.

If the issue still appears after disconnecting:
Close your game, log out from Steam and back in again, start CS:GO and attempt to connect again.