We feel your pain. I still have fits with the Apple TV disconnecting from the wifi, and have to restart it daily. And it's already been replaced under their program for that problem. Tonight I gave up and went back to Roku.
It's a problem with TCP/UDP port.
If you are using WINDOWS series, go to Firewall Setting, and manually add in TCP port 3689+TCP port 123 and UDP port 5353+UDP port 123.
Both TCP and UDP ports 123 are made for MAC,but I think, for safety usage, just add them in at the same time.
My computer and Remote App keep having some issue between each other until I set up those rules and they finally willing to settle down haha.
If you still don't know what I'm talking about, you may simply read the page below and follow the instructions again.
Troubleshooting Home Sharing - Apple Support
sorry for this poor description, English is not my mother language after all.
Retrieving data ...