I'm now having problems with this for over a week. I'm running a minecraft server on my computer. Therefore I used no-ip.org to have a "fixed" ip. I forwared all ports for the server and my friends can access without any problems. Later I thought I could make a little Homegape for statistics and stuff. So I installed xampp. I forwarded the ports 80, 8080, 8000, 7171. I (and everybody else in my local network) can access it via the no-ip.org address. But nobody else! (And I want to repeat that people can reach my computer over the minecraft port (25565) and no other port!)
How can I fix that problem? I'm pretty sure there is a simple node in one of the config's which I haven't seen yet. I googled for days. So I found out that I should forward these ports. But that's all I could find.
My firewall is (for testing of course!) disabled!
I solved the problem.
I am using cox and they are blocking port 80. Well now I am using https and port 443 and everything works fine!