MacBook Pro M1 + Dell D6000 + LG Ultrafine 24" Issues

[czazic11]

I have the same Monitors on my MacMini M1, using a Startech dual displaylink adapter, primary monitor is connected to Thunderbolt on the mac same as you.

Firstly, It wont work correctly even when it does "work", you can only select 3840x2160 (which just gives me a black screen), or 1920x1080 low resolution not HiDPI so it looks garbage. I tried SwitchResX which lists the correct HiDPI resolutions but just gives a black screen, apparently this is a M1 issue with the displaylink driver as people have reported it works fine with Intel Macs.

EDIT: Apparently the extra resolutions are just hidden, they show up fine on Monterey beta. The black screen I am getting at higher resolutions may be due to the Displayport -> USB-C cable I am using (Cablematters) I have ordered a certified displayport cable by Moshi to see if that helps.

You will need to plug the cable from the displayport on the Dock to one of the two thunderbolt ports, not the USB-C as they are output only.

If its not working you probably have the wrong cable, it must be a bi-directional Display port to USB-C cable, most of them are only for USBC output to Displayport which is the wrong way around.

If display link shows monitor detected, but the screen is black then you have the same issue as me which is that the 4k resolution is broken. I had to click gather windows on the display prefs window on the thunderbolt connected monitor, then manually change the resolution to 1920x1080 on the window for the display link monitor.