Update:

For those who have DSL installed, and who need to use those little inline "filter" boxes, I have made the following discovery about HPNA with Rio Receivers:

The line between the Rio Receiver and the Rio Central (or the PC server) must not pass through one of those DSL line filters. Arrange it so that the filters are on the telephone's line only, and that the Rio Receiver and its server connect directly to the main house wiring.

If you need to place a telephone and a Rio Receiver on the same outlet, daisy chain the phone through the Rio Receiver, with the line filter on the phone side of the connection.

This also counts for some DSL modems which have a pass-through "filtered" telephone port built-in to the modem itself. Treat the modem as if it were a filter, and use a Y-adapter if necessary to split off the wiring to the Reciver or Server before it reaches the DSL modem.