Hardware configuration is as follows:
- Receiver, is connected via HDMI cable to ..
- Apple TV, which is connected via Cat 6 ethernet cable to ..
- Time Capsule, which is connected via Cat 6 to ..
- Cable modem
- and also via Ether-to-Thunderbolt adaptor to ..
- MacBook Pro early 2013 which is connected via USB to ..
- an external WD spinny drive containing all my media.
(No wireless technology in use. All devices are on the same local subnet.)
The MBP is running Plex Media Server to serve recorded movies and music that are stored on the external USB drive.
When I want to hear music through the speakers connected to the receiver, I first power-on the receiver, then screen-share into my MBP, start the Plex Media Client, select music, and start it playing. Then I go to the MBP's Sound item in the Menu bar, and switch it from "internal speakers" to "Great Room" (the name of my Apple TV). Music comes out.
Then, three or so minutes later, it drops out. I go back to the MBP and the Plex Client has stopped. As if I'd punched the stop button -- nothing very out of the ordinary.
Here are the alternate methods I've used to play my music:
- Running VLC on the MBP, again directing sound to Great Room using the Sound menu.
- Running the Plex app on the Apple TV
- Running iTunes on the MBP, but instead of using the Sound icon in the menu bar to direct the sound to Great Room, I use an icon in the iTunes window whose tooltip reads "Choose which speakers to use" to accomplish the same thing.
In all cases, the audio drops out after a short time (3-5 mins).
In what must be a clue of some kind, this doesn't happen for podcasts (which, unlike the music, is coming down from the Internet).
There are so many components, and so much magic involved, that my intuition fails me. Can anyone suggest another experiment that might possibly narrow down the cause any?
UPDATE After it was suggested that this pointed to HDMI, I have tried both plugging the HDMI cable into a different port on the back of the receiver, and replacing the HDMI cable, without success. This leaves the receiver itself, the ATV, and the Time Capsule/router to be ruled out.