Hybrid-inter-nvidia makes external screen black

I need CUDA and an external screen for my Blender job. But I can’t have both because Nvidia driver issue. Here is the result of mhwd graphic driver that I have tried:
video-hybrid-intel-nvidia-450xx-prime CUDA is detected but external screen goes black
video-nvidia-450xx CUDA is detected but main screen goes black
video-linux+video-modesetting CUDA is gone but both screen works

My laptop is Acer Nitro 5 (AN515-52)


I think this is not the way to go:

In the old forum there was a tutorial or two how to get optimus-manager to work.
See here: