Possible solution for ATV dropping connections
I've tried everything over the course of several months and this one looks the most promising.
Possible Fix:
1. Open "System Preferences"
2. Open "Network"
3. Click on the "Sprocket with down arrow".
4. Select "Make Service Order"
5. Move the connection your using (Wifi, Ethernet, etc.) to the top, and click Apply
6. If you selected Ethernet, then turn OFF Wifi in the top menu
7. Shut DOWN your computer and then restart after completely shut down.
Let me know how it works for you.......hopefully this is what were looking for. So simple if it works!
MacBook Pro, OS X Mountain Lion (10.8.3), 2012 15.4"2.6GHz i7 QC HRA SSD256GB