An error occurred while connecting to the AirPlay device...

I have been using AirPlay for quite some time and today the connection between my iMac and one of my Airport Extremes keeps dropping.

The connection is noted as "excellent." It is the Airport model that looks like a white box that plugs directly into the wall outlet.

I can play without error from my iPad, only the iMac seems to have errors.

I can connect easily, start playing and about 2 minutes into the song I lose connection. A yellow triangle displays next to the Airport and the message, "An error occurred while connecting to the AirPlay device..." displays when clicked.

All software is up-to-date.

Any advice?