I’m not really used to finding a server with the IP, I usually find it in the list, so I ask you, how do I find a server with the IP that was given to me?
You can try “connect <serverip>:<port>” in the console within Garrysmod.
Another method, if you prefer, is to go to Favorites tab on Steam’s Servers window. Right click, then click on “Add server by IP address”. On the prompted window, type in or paste the IP address given to you, then click on “Add this address to favorites”. The server should now appear on your favorites window.