Hmm that's weird since 1,2,3 and 5 run on the same machine, melee on a different one.
Hard to tell what the problem could be.
Maybe one of the server list filters is checked that hides empty servers or something?
Also what you can try is going to your network adapter settings again, press alt when the window is open, then go to Advanced ---> Advanced settings
and move the network card that you use for your internet connection (the one connected to the router) to the top of the list using the green arrows.
That will give it priority over anything else that might interfere.