Unable to enter the server

It has happened to me on many occasions today: I'm about to join a game but for some reason, the loading screen does not appear. Instead I get a blank screen with a message "Unable to connect to the server" saying that it might be the firewall. It happened to me 3 times today and I got a "I agree to not leave games" even though the problem is the server not loading, not me leaving on purpose.

Can you please help me out here? It has been happening too many times