Apple TV Across Networks

How to make Apple TV work across network boundaries using iptables and mdns-repeater.

The Apple TV exists in somewhat of a gray area in a home network. It is both a media player which you might screencast to and a hub for HomeKit IoT devices. If you happen to segment those two networks for security reasons, where do you put the Apple TV? It has to be able to directly reach all the IoT devices but user devices should…