hello nate
First of all i would visit the site ive just pasted below, it is walk threw for setting up your router to work with winmx
http://portforward.com/english/routers/port_forwarding/USRobotics/USR8054/WinMX.htmAlso routers are notorious for not always being very good at handling alot of concurrent tcp/udp connections. The difference in what a router can handle from make to make is quite dramatic. It may just be that your router is not suited for running a primary connection,
Id also try redoing any firewall rules you may have already set, including windows firewall it has a tendency to be crap and forget its name and ports even if it was switched on(*sarcasm* lol)
Also check if their is a firmware update for your router, i have in the past had issues with net gear routers and they are quick are releasing newer firmwares their than ive seen from any other company, it may be that us robotics have released one for yours an is due a update.
Few things for you too look over their and if you still having problems post back