Ubuntu 21.10 + nvidia xserver 11 (495.46) + scaling for 4k external monitor

I have laptop HP Omen 15 (based on AMD 4800) with GeForce RTX 2060
built-in monitor - 1920x1080
external monitor - Dell P2415Q 4k

I need to get 200% scaling for 4k external monitor
By default it works correctly with fractional scaling when used the AMD driver.
I faced with some issues on that configuration and want to use NVIDIA for external monitors.

But when I set “NVIDIA (Performance mode)” the fractional scaling doesn’t work in Ubuntu display settings correctly. When I set 200% only for external 4k monitor - the buil-in monitor scale too.

I try to disable fractional scaling in ubuntu and use the nvidea x server for scaling.
But I can’t imagine the combination of nvidea x server’s setting for achive it.
Only the 1/4 part of the screen is used.

Please give me the example of configuration. Do I need use specific values for ViewPortIn/ViewPortOut/Panning?