[phzfn]

Originally Posted by tktan

Fix : install RDM (https://avi.alkalay.net/software/RDM/) take ur own risk

This is not the most recent version of RDM. The (open source) software was developed further by another developer. Here is the current GutHub Repository with a version with Apple M1/macOS Big Sur support.

https://github.com/usr-sse2/RDM

Originally Posted by Ryan0751

This is unfortunately not a solution for me.

I am able to select 3840x2160, which is too small for my eyes. Or I can drop it down to 1920x1080.

Using RDM, I see the same resolution options as other programs of this type (EasyRes, SwitchRes X). I can select alternative resolutions that aren't shown in the macOS system preferences, but they are NOT HiDPI (scaled), and therefore look very fuzzy (unusable for me).

I did a lot of testing. With RDM 2.5 (see link above) one can create custom resolutions, what would theoretically solve the problem and allow to create a custom HiDPI resolution. This works with the Apple M1 and Big Sur. However, the DisplayLink driver ignores those customizations. I already informed the DisplayLink developer team about this and hope that they fix this soon.