I've been having this problem for well over a year and a half now, with two different routers. Every so often my Internet connection randomly drops during normal use and I see this: but it happens 100% of the time when downloading from Steam. The download will start normally for a few minutes, usually peaking at 3.6MB/s, and then after about 5 - 10 minutes the Internet connection will drop and stay disconnected for about 10 - 15 minutes at a time. It's becoming more and more frequent and I've tried everything I can think of, including router and modem reset, downloading through a VPN and a proxy, even going so far as to buy a whole new router, but the problem persists. Someone suggested that it's possible that my ISP thinks I'm torrenting too much and is purposely throttling or killing the connection, which I find unlikely as I very rarely torrent and it happens most often with Steam and never with torrents or direct downloads through browsers. When using other connections away from home, Steam downloads work fine.
If anyone has any idea what could be causing this and how to fix it, pleeeease let me know as it is driving me insane. The added time the disconnects add to download time turns my 33Mb/s connection into an effective <1Mb/s connection (it took almost 4 hours for me to download BioShock Infinite, for example, at an average 3MB/s that should have taken just over an hour and a half.)
Edited by Malcolm - 6/1/13 at 4:10am