My friend has struggled to play CS:S and Halo 3 ever since he got them because when he joins or hosts games it drops him from the game or disconnects him. Other games work fine such as Guitar Hero 3 (Xbox 360). I opened the ports on his router/modem thing he rents from Comcast to no avail. I brought over my router and modem and hooked it up to his internet and it worked fine, he could play both games. Do you think that there is something physically wrong with the modem/router thing he has or it is some software issue that can be resolved with settings?
I bet it's an issue with his router since yours seemed to work fine when you brought it over. Instead of hooking both the router and the modem up, try just the router or just the modem and see if it works.
Also, since you friend has cable (I'm assuming this since you said he uses Comcast), he may want to contact the provider for assistance. He could have too many used cable outlets in his house and need an amplifier in order to use his net. I'd look into this as well.
