Apple TV (headless) + Home Sharing + Remote stops playback after one song I have the following setup: 


iMac (2013) with iTunes (11) and Home Sharing enabled
Apple TV (3rd gen) with Home Sharing enabled, no HDMI connected only optical digital out to my DAC
iPhone 4 with Apple Remote app
All devices are on the same wireless network (Jensen Air:Link something, might be replaced soon) 


The problem: I connect to the Apple TV with the Remote app on the iPhone. After a short period, I can access my music library (located on the iMac) and play songs from it. It will play fine for a song (or two), and then it just stops. 

(Remote app will typically display the song after the one that was just played, as if it was playing (the pause symbol is displayed) but there will be no "progress" indicator. Pressing pause does not have an effect. Skipping back/forth will change the song title/icon in Remote app, but nothing is played. After clicking around in Remote app, trying to restart the playback, sometimes playback starts again, sometimes the app terminates (I haven't found any patterns for what works here yet, it seems somewhat random). After restarting the Remote app and/or playing around in it for a while, I can make the playback restart, but it stops again and the process repeats.)

I've read about various ports that need to be opened in the firewall etc., but I don't think any of these apply, as everything works fine for a while. AirPlay to the same Apple TV also works (for a while). There's no firewall enabled between any of the devices on the local wifi network.

I'm starting to think this could be a problem with the Apple TV running without a TV/screen connected on the HDMI port, and that some kind of "screen blanker" or power save mode is triggered. 

Now, the questions: Does anyone know how to make the Apple TV run problem-free in headless mode (no TV/screen)? Is this even supported? Or would I be better off buying an AirPort Express and connect that to the DAC?
I suspect your problem is the network, not the devices. The queue used when controlling the AppleTV from an iOS device is different from the queue on the native Music app (to see this yourself, note the empty queue in the AppleTV music app when you start music from your iPhone).

So, you have two dependent links (at some frequency, not necessarily constant):


iPhone to AppleTV, to update the queue, provide new information, etc.
AppleTV to iMac, to retrieve requested files


Can you monitor the network links on these devices using your WAPs diagnostics features? Or, perhaps more usefully, using Wireshark or the like to promiscuously capture the conversations? I'm willing to bet there's some severance going on.

Regarding running the AppleTV headless, I'm certain that's not the anticipated use of the device, but I'm not aware of any specific problems this could cause, unless it expects video signal via HDMI to keep alive, which you could test easily enough.

Hopefully, this is somewhat helpful in considering your problem. Good luck!