A quick reply to my own post, now that I have successfully gotten this working. First off, the model that did NOT work is the Netgear XAV1501. I returned that and purchased the Zyxel PLA-407. I had never heard of that brand, but setup was easy, and everything 'just worked'. Been using the Zyxel Powerline adapters for about 1 week, and no problems at all. Glad to have the extra wifi coverage. And I love how my devices seemless switch from my primary Airport Extreme to the Airport Express as needed.