I am very hesitant to ask this.. sorry.. not quite a NOOB here... but still

[ActionA]

[solved] "Sadface" after a system update

Your router webconfiguration page should contain the ability to see all devices and their IP addresses. You’ll have to figure out which device is the one you are looking for. Alternatively, type arp -a into Terminal on your Mac and you’ll see a response that lists all known devices on your LAN. Again, determining which is the ATV is up to you.