Originally Posted by TomL.
Game servers will often use the same ports as the client or other game servers.
You can change the port of your client by addding +clientport 270XX to your client launch options.
It's recommended to use any port between 27005 and 27032 except 27020.
Thank you, it turned out the problem was that the server and the game used the same port, thank you very much, the problem is solved. Is there anything I can do to thank you?