all you have to do is OPEN the PORT the mic runs on in the router:
FIRST thing you need to find is your PS2's IP address. You can get this in the PS2 "network configuration", write this # down, it will be like 192.168.x.x
Secondly, you have to goto your ROUTERs config settings, usually you goto your internet browser (a.k.a. URL), and type
http://192.169.1.1
this is for a LINKSYS router, I believe D-LINK is the same, check in the manual on accessing the router config.
Third, usually you leave username blank, and type "ADMIN" in for the password to access the config (again, this is for linksys, D-Link might be slightly diff.)
Fourth, find "Port Forwarding" in your config, and enter the following:
check the boxes (UDP, TCP), and type in your PS2's IP for the IP. Type in 6869 for the PORT #, make sure that all the necessary boxes are check, click APPLY.
fire up the PS2 and your mic should work!