Maybe try to implement Netdata monitoring so you can see on your PC what is happening with your N2? It allow you to see all hardware parameters.
Also:
- do you experience the same results with all kind of content (x264, x265, avi) with all kind of parameters (resolution, bitrate)?
- is it the same if you watch content located on microSD or local USB drive?
- did you try to flash CoreELEC on another microSD? Is it the same result?
In general: you should try to narrow down potential root cause…