It's basically an OS crash... which makes it a Roku problem (as it is the OS). I suspect many of these tvs may also have a memory issue. Similar to running an application on your computer without the ram to handle it. The standalone Roku's (other than the sticks) have a memory slot to allow the additional of a memory card. Many of these tvs do not.
i've seen a lot of junk responses on here. idk if you have found a solution or just got a new TV (worst advice ever, like saying, "oh, computer trouble? just reinstall windows.") so if so, then this reply may still help someone.
after having the same issue for weeks, i had been dealing with it, but tonight it was bad. since i use my RokuTV as a secondary monitor, it is set to be on HDMI1, and that's all i use it for now, but it kept loading other channels, muting, and powering down. after i did hit the reset button, it was still happening. so i chose HDMI1 again, and then hid the remote under a shirt. still happening. then porn showed up. and it was the same video 3 times. so i thought it may be someone here in this hotel, so i put the shirt over the remote sensor. problem solved. another thing to consider is that you may be having the random things happen because the other person is testing buttons and powering it down because theirs is not acting right because of your buttons being pressed, and being on the same wifi network may not be helping.
I ended up disconnecting the Roku and started using Samsung smart TV apps. I’ve been avoiding them simply because I was so used to Roku, had Roku devices ever since I cut my cable 10 years ago, but guess what, the TV apps now work just as well.
The problem is certainly on Roku’s end, as my new Samsung doesn’t turn on and off without it attached, and works just fine with Xbox as well.
Honestly I doubt that I will buy another Roku in the future, I just don’t see the need anymore. If not for this problem, I’d probably never started using Samsung apps, as my first experience with them years ago was awful. So, Roku pushed me towards their competition... the irony.
I have a 43" ONN Roku TV in my office and it usually turns off and on on its own around the five minute mark then it stays on after that. It's weird. I also have a 65" ONN TV in my conference room and it has never done this once and bought them the same day and the same Walmart store. Finally, I own three ROKU TV's at home (Various sizes and brands [Insignia and Sharp] and a ROKU Ultra device and none of them have ever done this. This post doesn't solve the problem, but at least you know the experience that I have had the 43" TV.
I have a 72" Roku. Mine started turning off after I had attached a bluetooth transmitter to use headphones. As soon as I disconnected this, it stopped. It only does this when the transmitter is connected.
To everyone else here, check for any bluetooth you are using near by. This may be the culprit. Still a Roku issue. Who makes a TV without the possibility of using wireless headphones anyway?
Yes, I have noticed this issue as well. It may be on ROKU's end, but it must be the App's end on the Roku device. Here is what I experienced on two different smart TV's. I enjoy watching TV from the Pluto app. And noticed, it is happening from the Pluto App. To verify this issue, I changed the channel to Sling or Netflix app and it stopped turning on and off. It is always best to test other apps, which make me think the issue is from the app. Pluto app may need an update. Has anyone else tested various apps? Is this issue happening on a different app? Curious.