Home sharing between IMac and Apple TV

Dunno, but i tend to just stop/start iTunes to fix it.

Hope you get a good solution, kind of glad someone else has it

 

I can't say I've had this issue, but the fact iTunes had to be on at all for streaming made me use a different solution; Plex & Airplay.

 

I have an iMac connected to my Apple TV via Home sharing. Works very well and stable.
I am sure you know that your iMac has to actively run (have open) iTunes for it work.
Your iMac goes to sleep and in order to see the Movie section of iTunes it has to wake up.

I use a Time Capsule which reliably wakes up my iMac when the Apple TV connects.(TC runs a process which remembers who is who on the network and then sends the "wakeup on lan" package to the iMac)

This might not work reliably with third party routers.

a workaround which other people have used is to run a VNC client like "My PocketCloud" on you iPhone/iPad and remote connect to your iMac. That will wake it up.