Hi Jerome,
I would suggest that you try again using the current software. In my case I had success testing four of the images using the procedures documented in the wiki.
https://wiki.friendlyelec.com/wiki/index.php/NanoPi_R6S

I ran a quick test on the Debian 11 image, and found that the preinstalled mpv player supports 4K video without noticable issues.
My testing was done on the May 9 build.

You must not have found the R6S wiki page. Link to wiki: https://wiki.friendlyelec.com/wiki/index.php/NanoPi_R6S I found the descriptions on that wiki page to be quite detailed including the OS installation procedures and a link to the image files. I tested Debian 11 from sdcard, and also loaded tha...

The May 9 release works with pi/pi.