[Gmod-help] Muliplayer Server Issues!

[nproto at charter.net]

         Hi, I just had a very important question to ask regarding mutiplayer play in gmod. Multiplayer works fine in my game, but when I try to join a friend's game, or if he invites me to just play with him, it says the sever isn't responding when I try to join a game. When a friend invites me to a multiplayer sever with other people, it says it's responding, but not when he's alone. We try to invite each other to mutliplayer servers we create, not single player games, and it still says it's not responding. I really want to play with my friends, but not with all these other people. Could you please help me! I would be so grateful! I love gmod and I just want to make a better exsperience for myself and my friends. Thank you so much if you can help me!