"Start Multiplayer" Problem

Hello everyone!

I have a problem with the “Start Multiplayer” option in “Start New Game”

I will explain simple as possible:

When I go in “Start a new game” do all the option, selecting a map, I press “Start Multiplayer” (Supposed to be Listen?)

But, my friend can’t join my game, here the problem.

They all having the same message saying “Failed to connect after 4 attempts” or something like that.

But in Killing Floor (Listen Server), I can do server and everything is working well.

If you have the answer to my problem, please help me.

Thanks you! And long life to Gmod!

You need to open/forward the ports for Garry’s Mod.


connect <ip-address>

It needs to be your external IP Address, not the internal (not 192.168…)

when you start up your game type

 sv_lan 0

Give your friend this IP number below:


Thanks everyone for your answer, with the power of the community I resolved my problem!