[than3]

That's very common, do you know the general why?

Usually the power brick is poorly isolated and/or you have dirty electricity, it results in errors on an ongoing basis that get logged to the small amount of onboard memory. (not usually a circular buffer.)

When the errors have sufficient volume the memory fills up, and it stops working at resource exhaustion.

In a real pinch, I've resolved this in some of the more milder cases by simply using one of those walmart plug timers that turns off for a few minutes in the morning when everyone is asleep.

[hot_gril]

Well, at least they were on UPS and got power conditioning that way. But there's also just crappy programming. It's not only ISP-provided stuff, it's cheap home routers in general. I don't trust them.