[alturismo]

natively the pc here would be also 2160/60 of course, but as mentioned the quality of 1080 material is worth then ..
and as mostly stuff here is 50p i dont want to always have refresh active on every change, thats why i use 50 and not 60.

And setting the PC to 1080p and set refresh on start stop, the resolution also changes when playing back 2160p material (movie, desktop, kodi, ...),
so that works as it should and the TV reports also input correctly,

If i set windows to 2160p everything i always 2160, as the TV shows the input 2160 then im pretty sure the upscaling is also done by the gpu and not by the TV, cant imagine how that should work this way,
also when i remember the old dsplayer days with kodi 16 in combination with madvr and all the settings for upscaling to get the best quality.
as i tried the dsplayer madvr option ~ 1 1/2 years ago with an GTX960 and my Sony 65S9005B i had to adjust alot in madvr to come close when using 2160p default
compared to native 1080 output and let the TV upscale, on the edge what the cpu and gpu could handle ...
always talking about 1080 material ... 2160 always looking great as theres no upscaling then needed

hardest job is the LiveTV 1080i material, here is the hard difference between 1080 and 2160 default resolution, that u probably cant follow as NTSC is a different story.
im using TVHeadend as backend and kodi as frontend.

fo ripped movies and so on theres no real difference who upscales (PC or TV) ... but LiveTV theres a real difference, dunno why but my experience.

but may things have changed and i ll give it a try setting all to 2160 and see if thats the clue, on wednesday i have some spare time to give it another try.

Thanks for trying to help.