My kids are complaining they are "glitching" and getting kicked off Xbox Live lately. This seems to have started to happen shortly after installing an Asus RT-N56U router. I haven't enabled QOS but I never did so on my old Linksys that it replaced and they never had problems. I've run speedtest on a computer connected via Ethernet and I'm getting 35mbit download and 6mbit upload from our Comcast Xfinitiy, which it should be. However, I do admit that we seem to have slow Internet after heavy rains on some occasions (probably a rotten cable underground), BUT, they have had the connectivity issue multiple times when the Internet connection tested fine.
Actually, come to think of it, the problems didn't start until they got the new Call of Duty II that came out a month or so ago! But I just confirmed it happens with ALL the games, like Minecraft.
The router is about 25-30 feet from the Xbox and there are 4 walls inbetween it. In the same room, there's a notebook computer an additional 15 feet away that works great and all our tablets and phones work fine.
So I'm trying to determine what has changed as this router it highly rated and the Linksys I came from was not suppose to be as good of a router but they never had these issues!
Any suggestions on how to troubleshoot more and or what settings to experiment with is greatly appreciated. Maybe just too many kids in the neighborhood on Xbox Live now? LOL But they said their other friends aren't having the same problem.
Oh and yes, I have the lastest 3.x version of the firmware installed from Asus. This happened before firmware upgrade too. Router is set to bind both bands to same SSID. WPA2-Personal Security. Auto mode with B/G Protection. QOS off. I do stream Pandora and do a lot of browsing from my home office as I work from home, but I haven't seen a pattern of them NOT having the problem when I'm off my computer. No one else is doing anything like streaming video, etc, or backing up large files to a cloud or something.
You should also contact Comcast and have them do a line quality test on your underground service , any water damage inside the cable will cause havoc with your internet service.
This link has some useful tools to help in diagnosing any internet issues .