At work or school

If your Apple TV is connected to an enterprise or campus network, make sure your network, router, firewall, or proxy server are configured to allow communication over these TCP and UDP ports. 

You can also use Configurator to create a first time configuration for your Apple TV devices. Connect the Apple TV to your Configurator server using USB, then set up the device using a profile.

If your network uses port address translation (PAT), make sure that UDP source ports are translated to port 123, or in the range of 1024 through 65535.