After a while (can be days, can be weeks), my network access speed slows down to ~2Mbps. Power cycling the modem (router and modem power off, then modem on, then router on) improves the performance to about 15Mbps. I'm curious what is the underlying reason for the slowdown...
Edit: Router and modem are both Linksys (CM100 and WRT320N), the OS is Windows 7. Provider is Comcast. I've had the same symptoms with the old hardware (Microsoft router, and rented RCA modem). If you search for "power cycling" you can find a lot of articles, speculating if it helps or not. In my case it clearly helps - but why?