hey, nope i disabled all firewalls for the tests. On my router i opened TCP/UDP ports from 2300-2400. I also tried it with an ad-ahoc-network between my laptop and my computer. The final, published exe of the multiplayer-tutorial from aum75 works everytime, but not if i publish it with my own editor. They should use the same ports, should'nt they?

Good to know that it works for you, so its not the engine's fault?!. Maybe my key-file is damaged or i'm just too stupid^^