Q: I just got my router and I’m having a hard time playing DirectX 7
games (most Microsoft games made in the late ’90s). How do I get rid
of these firewall error messages?

A: I typically wouldn’t recommend opening more ports than absolutely
necessary, but for some games or applications, it’s essential.

If you just got your router, chances are you’ve checked out the router
configuration utility that’s actually loaded in the router itself.
There, you’ll find several options, and depending on what sort of
router you have, the option you’ll be looking for should be located
under some security tab - or even one called applications and gaming.
If all else fails, look for an option called “Port Range Forward.”

Once you’ve found this option, there should be an option to put in the
IP address of the machine from which you want to use the game. To
quickly find out your local IP address, go to Accessories, then Command
Prompt, and type in IPCONFIG using the IP address specified. After
you’ve entered in the IP address, there’ll be two options: one for the
starting port, and one for the ending port. For DirectX 7 games, both
boxes should have the port 47624 entered into them. You’ve now set up
the initial port forwarding for DirectX 7. Next, you need to set up the
subsequent port forwarding.

On the line below the port forward you just created, there should be
the same boxes. Enter the IP address you used for the first port
forward, then, for the starting port, enter 2300. For the ending port,
enter 2400. Submit both port forwards, and you should now be able to
use DirectX 7 games online!

Keep in mind that if you use your router as a DHCP server -
automatically sending out local IPs - these port forwards will not
be permanent. What you need to do in that instance is to go into your
network connection settings on the computer where you are trying to
play from, go into TCP/IP properties, and make sure that Obtain IP
Automatically is turned off and manually enter all of your settings.
If you’re unsure of what those settings should be, go to your command
prompt and enter IPCONFIG /ALL and a full list of all of your LAN IP
settings should appear.

Further resources on DirectX port forwarding can be found
here.

A full site describing port forwarding in depth can be found here.

Don’t worry! It all sounds complicated at first, but once you’re
laying seige to small cities and villagers, or building up your space
aged army with all of your closest friends, you’ll say it’s worth it.
[Jared Hudgins]