sudo apt-get install xserver-xorg-video-dummy
Create / Edit xorg.conf file Rename file if already exists for backup
sudo vi /usr/share/X11/xorg.conf.d/xorg.conf
Add the following content to the file Set the resolution to what you like (whatever resolution the screen is that is used to connect remotely is probably is a good idea)
Section "Device"
Identifier "Configured Video Device"
Driver "dummy"
EndSection
Section "Monitor"
Identifier "Configured Monitor"
HorizSync 31.5-48.5
VertRefresh 50-70
EndSection
Section "Screen"
Identifier "Default Screen"
Monitor "Configured Monitor"
Device "Configured Video Device"
DefaultDepth 24
SubSection "Display"
Depth 24
Modes "1920x1080"
EndSubSection
EndSection
Save the file Reboot and Test
Just found this, and it immediately fixed my issue not being able to connect via RealVNC to my new miniPC. Thank you for that! I do seem to be locked to 1280x720 as well. But it's a good compromise for now. Would love to know if anyone finds a solution to the max resolution. Thanks to all who have contributed here as well!