Remote to Ubuntu Desktop shows “No display” when no HDMI monitor is connected

[Mocca-K]

I’m currently using RustDesk to remote into an Ubuntu Desktop machine.
When I connect to the Ubuntu device without an HDMI monitor plugged in, the screen only shows “No display” (black screen).

It works fine when a physical monitor or dummy HDMI plug is connected.
Is there any recommended way to make RustDesk work (without a display connected)?

[rustdesk]

All solutions are here, https://github.com/rustdesk/rustdesk/wiki/Headless-Linux-Support
Some might work, might not work.