Thank you very much for your replies.
I seem to understand the problem a little bit better now.
(Must be something with the highest available resolution, which in my case case has a 16:9 format)
So i tried the step, where i create a custom resolution. (DSR | CRU)
Just anything higher then the current maximum resolution in a 21:9 format.
The nvidia control panels offers some kind of "pre setting",
which allows you to set a higher resolution based on a factor of the native resolution (like 1.25, 1.5, 1.78- and so on).
But since its based on the "native resolution" , it is creating only 16:9 formats. (I tried all possible choices)
(The highest standard resolution i can choose is 3840x2160 which appears to be my "native", which is complete balderdash since it is a 21:9 3440x1440 display.
Also in another setting it tells me that my native resolution is 3440x1440.)
So i tried to create my own custom resolution, not based on any factor, in another setting of the nvidia control panel.
--> 5120x2160 @144Hz
But when i try to apply this setting, the control panel tells me, that this resolution is not supported by my display.
The only possible way now seems to be deleting the 3840x2160 resolution from the system anyhow, but i really dont want to dig around and juggle with any hex codes and what not.
(Its not that i am too lazy. Its just that i really tried alot and failed to understand the matter completely)
Is there any way by not changing any hex codes?
Am i on the right path in your opinion?
Is there any way around this?