I'm getting that, but in a client's internet connection.

Here's a quick summary:

- his connection goes out randomly, when he's using it and when he's not
- when it goes out, it goes out for all wired and wireless devices
- I arrived during one of these outages, and I could log into the router's admin area
- the router seemed to be getting WAN info from the cable modem
- this was the second router and the second modem, yet the problem persists
- today he put in a THIRD router and modem combo, and it's still happening
- power cycling the router fixes the problem

This makes no sense to me. I've tried all the diagnostic approaches I know of, but haven't thought of anything. Any ideas?