I’d like to encourage everyone to use the Discord as you’re likely to be helped there much faster. http://discord.gamemak.in
If you get the error Could Not Connect To Server, then for some reason your server is actively rejecting the connection. Generic Shooter doesn’t do any rejection like this so this indicates a deeper problem. Check out your logs to see if they show why. If you have Steam enabled, most likely Steam is preventing session creation and joining because Steam does not allow the same Steam account to be ‘playing in two different places’, even if those places are on the same local machine.
The Create Session / Host game logic exists in the Host Game widget.
The Find Session / Join Session logic exists in the Server Browser widget.
The Quick Play game logic exists in the Quick Play widget.
I personally don’t like this logic existing in the widgets so I’ll probably move it out of them at some point in the future.