So whenever I try to join my friend on Gmod, the steam thing showing the server says "server not responding" every single time I try to join whatever server he is in. Whenever I google this problem, everybody else seems to have trouble joining their friends' private servers, but this happens to me even when he is on a public server. I've tried everything such as looking for the server in the list, refreshing the list of servers, and so on. He doesn't seem to have trouble joining me when I'm in a public server. Only when I try to join him. My game loads all sorts of servers just fine, except for whatever one he is in. Just wondering if anybody has any suggestions, could be something simple, I'm new to this game so any help would be appreciated.