I have cracked the nut of making EU2 and HoI work on Valkyrienet and hosting IP games. This is a reference on how to solve problems with your router's firewall.
First, open your router's administration utility.
Go into your web browser and type in the IP address of your router. This should be listed in its manual, but usually it will be
http://192.168.0.1/
Log in using whatever the default username/password is (usually admin/NO PASSWORD)
Now navigate the utility till you get to the status page.
Here you're looking for one thing: YOUR COMPUTER's Local IP. This will most likely be 192.168.0.SOMETHING. Make a note of what the something is and continue to the router's firewall options.
Here you want to make two seperate entries. The first will allow all traffic from the internet on TCP ports 2300-2400 to navigate the firewall, and then redirect it to your computer. The options should read:
Enabled
Allow
Source: WAN
IP Range: */* (For all ip addresses)
Destination: LAN
IP Range: YOUR LOCAL IP ADDRESS/(leave this part blank)
Protocol: TCP
Port range: 2300-2400
Schedule: Always
Do this again but change the port range to 47624, and you'll be set. Save the settings and have fun with HoI or EU2 (This works for both.)
~Sky