My stick is about 3 years old and has just started doing this.
I had the same problem. Moved my roku stick from bank of tv and plugged it into a short HDMI extention cable. Never a problem since.
I received the short HDMI extension. Plugged it in and it worked for a few days fine. Then I turned on the TV/Roku and had a message on the screen that the Roku was not connected. It was plugged in fine and wiggling it didn't fix it but unplugging it from the extension and directly back into the port fixed it.
I haven't tried it again. I also haven't attempted to play 4K video on Amazon Prime again either which is the only time I got the warning.
I have 4 streaming sticks and one Express Player. On one of the sticks I will occasionally get the HDCP or whatever message, and simply have to unplug the power to it, then re-plug it back in. Only on the one, which is connected to an older "flat screen" TV that I bought about 14 years ago or so.
I also have a stick connected to an HDMI-to composite-converter, for a CRT TV that can only accept video and one audio input. I have that stick connected to a power strip that I can switch off when not watching TV, because it has gotten to 107° when continuously left on. Apparently the device or TV that the sticks connect to has a bearing on the heat it can get up to, as at least one cause for the extreme temperature.
I've never had my Roku stick overheat until today and I've had it for at least two or three years. Kudos to the person who found it was specific apps like Amazon Prime, which is what I was using at the time it overheated. Thank you!!!
I have several Roku sticks that all have problems when hot. Losing connection and buffering are very common. Seems a small device has no way to give off the heat it generates.
This seems to be an ongoing thread/problem with the Roku stick...I just discovered it today. I've had a Roku stick for a couple of months, and lately noticed a problem with internet connections and latency with the remote...not severe, but off and on. I started to get an onscreen warning about my device overheating recently, so checked it out. Sure enough, it was hot to the touch. I had it connected directly to my TV (no extender) and into a socket. I tried removing it from the socket, and used the USB connection on my TV. This made no difference. I was sent an HDMI extender from Roku, which arrived yesterday. I tried it out, and within minutes, it had heated up. I checked the internal temp (I got the info on how to do that from an earlier post here). It was running between 95-100 C, which, if Google is correct, is around 200 F. This does not sound good to me. Other than toss it and go with an Amazon stick, since this seems to a problem with the unit itself, does Roku have any ideas other than what I've already done to help this problem before it causes damage? Thanks in advance.