Anything that requires Internet connection (i.e. Youtube, including casting from mobile device).
I just found out this weekend; with an older, cca 2013-ish samsung tv, connected to a network that has OpenWRT router with Adblock, and forced redirect of all port 53, 853 traffic to the local resolver. It cannot resolve its mothership (the rules were already in the Adblock list, I didn't add anything). The TV shows up a messagebox that it cannot to the Internet and asking the user to check the connection.
