> This. Why would you even connect TV to the network?

I happen to have a NAS with family pictures I like to display. I can (and do) firewall that thing, but then you hit other issues like the apps you need to show pictures and movies in the first place not to install/run.

I've yet to hear of a reasonable recipe to isolate and secure such connected TVs. And don't get me started on Chromecast or other Android dongles, I've no reason to expect better treatment from Google. Some open source hacked-together box, then?