Well… it would have been quite nice… a short round “Portal 2” together with a teammate in “coop”-mode over the internet…
But the #?#&! thing just doesn’t work :-(. Neither if i invite the other nor the way around… the connection simply doesn’t work.
If anyone has helpful hints about that… thank you!
Meanwhile the problem had been solved, also see: Portal 2 and the Coop-Mode – Update