How do I set up a Garry's Mod Server using this

I’m trying to set up a Garry’s Mod Server, but can’t figure out how to configure all the ports that Garry’s Mod needs (TCP: 20715, 20736 UDP: 27015, 27020, 27031-27036) while using one tunnel. I also need help trying to connect the dedicated server app to the Play-it App.

Thanks, in advanced!