Same issues for me. Apple TV is on a wired ethernet connection, others are wireless. Router is in the same room less than 5 metres away. I had no issues at all until updates to iOS 8. Reading the specs on the update, it seems to me that airplay is using higher bit rates for audio and video since the update, which 'may' cause network issues. On a wireless or wired lan there should be more than plenty of bandwidth overhead to cope with streaming a 192kbps MP3!
Everytime I first try to connect to it from my iPhone, it crashes the native music app causing me to have to restart the playlist on the app. I have no idea why or how it can cause that, but it does... every time on my first try.
I love Apple products but so far the Apple TV has been the biggest waste of money - I can't stream music reliably and video streaming is so bad I just resort to plugging the laptop in to the HDMI anyway. Hugely disappointed with it.
I must have some interference or something coming from somewhere, I don't know but I'm gonna try to the network tools to find out - trouble is that it's intermittent...