Belkin Router Wireless-G

Trying to be able to connect my and my mother's Wii's together. Problem is we constantly get an error message when trying to join eachothers room. Error Code 86420.

I did some more research after posting this, and it appears as though the router I own doesn't have the capabilities to open every port. Other versions of the same router have the range ability, whereas mine only has a maximum of 20 ports. I'm not sure the exact port, nor is anyone really. I have googled a lot of things and no luck. You would think Nintendo could narrow it down, but o'well.