From thread
On September 12 2004 22:34 SoL.Origin wrote:
on any client machine (ie not the router/server) go to start->run->regedit and find this key:
[HKEY_LOCAL_MACHINE\SOFTWARE\Battle.net\Configuration]
and in there make a new DWORD key, name it "Game Data Port" and its value should be in decimal 6112 or 6113 and so on, a different value for each machine, then you have to set up the router to make those ports work on those IPs
on any client machine (ie not the router/server) go to start->run->regedit and find this key:
[HKEY_LOCAL_MACHINE\SOFTWARE\Battle.net\Configuration]
and in there make a new DWORD key, name it "Game Data Port" and its value should be in decimal 6112 or 6113 and so on, a different value for each machine, then you have to set up the router to make those ports work on those IPs
So I used this in conjunction with portforward.com
And forward UDP 6112-6119 ports for my IP for my computer through my router and I can make games just fine.
For me, if you do one but not the other, you will not be able to make games.
Also in that thread mentioned above there's talk about multiple bnet connections behind the same ip. I think I've solved the problem by updating my firmware on my linksys router. Supposedly if you have the 2 users log at different times bnet assigns you different ips, but I've never known if it works.
If you're really desperate to play behind 1 IP, try the german or korean versions of your router firmware. The only downsides are that a) it might not work and b) your router's now in German or Korean.
I've also contemplated switching my router to a open source firmware. I dunno whether it works or not, but if you're interested, read up on it here
The other popular open source firmware (and by all means not the only) is DD-WRT. Both firmwares evidently allow you to stack the power of your router so that it reaches hard to reach places.
I've gone way past what I've meant to say. This is by no means a comprehensive guide and I don't guarantee any of this to work. Use all of this at your own discretion.