[Alcarimon]

I haven't been offered the Windows 2004 upgrade yet so I am still using v.1909.  I don't know if that upgrade or rolling back has affected anything but I doubt it.  Of all the players I'm using, only DVDFab 6 uses Windows HDR.  It switches on and off automatically.  Every other player uses nVidia API.  I haven't found any reason to upgrade my GTX 960 4GB so unlike newer video cards that require newer drivers, I can still use older drivers - 445.87 from April 2020.  From what I've read, newer cards with newer drivers can have problems switching HDR at times.  Did Windows upgrade your drivers when you upgraded to 2004 and keep those drivers even though you rolled back to 1903?  Are you using official stable Kodi 18.7 or older with external players and if so, which one(s)?  There should be no reason to ever activate Windows HDR except when it happens automatically using FAB 6.  Internet connection has no bearing except retrieving builds and drivers if you haven't saved previous downloads.  I can tell you although I'm no longer using 3D, nothing has changed in this guide and all is working perfectly for me.

Tks for your quick reply!
I always upgrade the Nvidia drivers but i’ve never had any problem after that.
Anyway i use the MPC-BE for external player with your wonderful LavFilter settings.
I don’t know if the kodi’s version is decisive because i used MPC without open Kodi.... but my kodi is 18.4
The situation is really strange: in a day all is ok and the day after it doesn’t work!! Mistero!!!