i have a dell vga monitor with hdmi adapter. it works but not recognized by system. i try to hook up a 2nd small monitor on hdmi but not working. Ubuntu server 20.04 with gnome on pi 4 8gb not even showing dual displays in display settings. have another on pi 4 4gb with mate---same issue not showing dual monitors in settings and not working. refresh rate is blacking out.
11 Answer
I had the same issue running Ubuntu server 19.10.01(64 bit) with Ubuntu Mate (sudo apt-get install ubuntu-mate-desktop.) The Dell monitor would stay active but have a black screen.
I found the answer here:
I modified the /boot/firmware/syscfg.txt(sudo -e /boot/firmware/syscfg.txt) and added the following line:
dtoverlay=vc4-fkms-v3d
