Roku is exploring ways to show consumers ads on its TVs even when they are not using its streaming platform: The company has been looking into injecting ads into the video feeds of third-party devices connected to its TVs, according to a recent patent filing.
This way, when an owner of a Roku TV takes a short break from playing a game on their Xbox, or streaming something on an Apple TV device connected to the TV set, Roku would use that break to show ads. Roku engineers have even explored ways to figure out what the consumer is doing with their TV-connected device in order to display relevant advertising.
If tv is talking home using ip directly, DNS blocking will not work. You have to ether disconnect tv from your network or give the tv a static ip and block all traffic to and from WAN (internet) from that device Update tv manually using USB stick.