A while after we switched to cable internet [*] our home network started doing this highly annoying thing--which it is doing right now, in fact--where it would cycle off and then cycle immediately back on, every minute or so. Sometimes rebooting everything helps and sometimes not. It seems to happen mostly at night (possibly there is a temperature correlation, as we haven't turned heat on yet?).Unlike when our DSL would go on the fritz, our internal network also vanishes when it loses the internet (that is, I can't see my desktop from my netbook), so I suspect this means the problem is the router not the cable modem?
[*] I thought I was getting an all-in-one modem plus wireless router from the cable company. The instructions were zero and so I'm not sure if that's what I actually got, and anyway I realized that we still needed the existing router because of the multiple Ethernet connections we use, so I just plugged the modem-possibly-router into the existing router and it worked fine. I'd think any interference from incompatible devices or whatnot would have shown up sooner and not be so intermittent.