Internet issues

[metalgearmac]

I am running warcraft 3 on os x. Any time I join any type of game after a minute or so of playing the message waiting for host.. and then a disconnect button under it appears, and eventually I am disconnected. I'm not sure if I have to open ports or what because I can join and play for a few minutes. I don't know if it is ports or my wireless connection. When ever the message appears my internet speed is down to 4.xx KB/sec. I done alot of searching around have not found anyone who has the same problem. I've tried not using the wireless but a ethernet cable and the same things happens with the speed and in warcraft. I have also tried running in dmz mode but the same thing happens. please help