Many Apple users have been experiencing networking problems, and developer Craig Hockenberry explains the cause in a profanity-laced tirade. The discoveryd service, introduced in OS X 10.10 Yosemite and iOS 8, is the root of the problems. Unfortunately, the more Apple devices you have on a network, the more likely it is that you will suffer these networking problems. So far, the only fix seems to be to reboot all of your Apple devices. If you have both an AirPort router and an Apple TV, you should turn off the Apple TV, reboot the router, and then turn the Apple TV back on.