Maybe this has been talked about, but I sure couldn't find it.
I have Comcast ISP with a Scientific-Atlanta DPC2100 series modem and a Linksys WRT54GSv7 router. I have had this setup for a while now, but in the last several months while I download any large files, the connection drops and the downloads stop anywhere between 10 and 45 minutes after they start. Watching the speed graph in uTorrent the download speed slopes off to nothing and the lights on the cable modem turn off, except "cable" and "power" ("send", "receive" and "PC" lights go out). The internet ceases to work from there on out - until I unplug and replug the modem then it starts all over again.
I called Comcast and they, of course, blamed it on the router after a few "tests" ensuring my connection was fine. He suggested a direct connection to the modem, which - reluctantly - I tried. Turns out it works just fine!
So it must be the router, right? I am, after all, on my 6th router in as many years. So I thought before I go and buy a new one I'd try DD-WRT, to eliminate a firmware problem. Well DD-WRT works fantastically, letting me change my NAT table settings (other people have suggested this with P2P problems) but still I have the connection issue.
But if it's the router, why does the modem seemingly "die" and not the router? I hate to just go and buy a 7th router...
I thought I had tried that. The problem has been going on for so long that I forgot the troubleshooting steps I took back then. I would live with it but I just found out it drops out playing Team Fortress 2 which makes me mad, lol.
Yea, it's puzzling because the modem says it's still connected to the internet and the computer says it's still connected to the router. I'll try resetting the router tonight and let you know.
I got it to happen again tonight (not hard, btw, lol) and the modem reset itself - all lights solid -> all lights off but power -> various blinking and such until just "power" and "Cable" were on. I reset the router and it flashed various lights along with the modem! The modem reconnected!
So it appears resetting either one will correct the problem.
Seems like the router may be causing the problem. Only way to be sure is just use the modem for a day or so connected to the computer and see if it occurs again, if it doesn't then it's got to be the router.
If you had another router laying around, or knew someone that had a good one just as a test you could try that as well before buying a new one.