The next step is to deactivate all firewalls,
and open everything on the router.

You should only do that for a short time.
But then you can usually connect to your server, and then
try to work you way up by switching on the firewall components.

Maybe you simply have the wrong IP of the server.
You could also try to use some kind of PC Game with multiplayer funtionalities,
to try it out.
The first step is to get a connection. The problem is obviously not 3dgs related.

Setting up a server through a router is usually a pain.
Thats why nfs42 is running the chatserver and not me.