TLDR; How can I get a headless machine to keep the resolution of a 4K monitor dongle to 1920 x 1080?
Machine running Ubuntu Desktop 22.10. Trying to set this up as headless. Initial configuration of the Ubuntu machine is done with a 1920 x 1080 (HD) monitor connected to it. I can RDP into it using MS Remote Desktop. All great.
The monitor dongle I have is a 4K version. When I unplug the HD monitor and plug in the dongle, the display reverts to the 4K resolution of the dongle. I can, via RDP select a resolution of 1920 x 1080 but as soon as I click "Apply", MS Remote drops the connection, and I cannot confirm by clicking the "Keep this resolution" in that dialog box so the display setting resets to 4K.
I can connect both the real display and the dongle and set the dongle resolution to 1920 x 1080, but, as soon as I unplug the real monitor, the system resets the displays and defaults to the 4K resolution of the dongle. Yes, I set the dongle as the main display first.
So, how can I get the machine to keep the resolution of the dongle at 1920 x 1080?