MOCA (Ethernet over coax) is a much better way to go than using the house power lines, and less compatibility issues. I have used both without a problem, but have been using MOCA for a couple of years. I use it for the Slingbox, Ethernet for the TIVO is not really needed with a fast WiFi. I'm using the Actiontec MOCA adapters.
Usually if there is a problem with the Cable signal coming into the house, it will affect the modem, not the router.
Is the router firmware up to date? Routers do go bad, as do splitters, and cable connectors.
