Powerline half-dead?

I have a pair of Netgear Powerline Adapters (XEB1004) that I purchased and set up last August. I use them to connect a TiVo and an AppleTV 2 in my living room to my router (in my office). All has worked perfectly from Day 1, until today.

It's quite odd. The lights on the Powerline are lighting as expected (at least most of the time; occasionally the Ethernet light stops blinking). According to the Settings screen on my Apple TV 2, I do have a working Ethernet connection. But almost all of the Ethernet-dependent functions of the Apple TV 2, especially those that depend on a connection to the Internet (as opposed to a LAN connection) do not work at all.

I checked the TiVo and it too has no Internet connection. So it is not just the Apple TV 2.

Further, when I switch the Apple TV 2 to operate over my Wi-Fi network, instead of Ethernet, the Apple TV 2 functions perfectly.

All other non-Powerline Ethernet-connected devices continue to function normally.

I have unplugged and replugged the Powerline and Apple TV 2 — to "reset" them. It had no effect.

By process of elimination, it seems I have a semi-dead Powerline and need a hardware replacement.

If anyone has any other ideas as to what could be going on, and how to fix it, I would be happy to hear it.