Please, this question has not been answered, I have read them all and none seems to work for me.
I have a headless system Ubuntu 20.04 with Advanced Micro Devices, Inc. [AMD/ATI] Richland [Radeon HD 8570D]
and I have installed the
sudo apt-get install xserver-xorg-video-dummy
with changes to the xorg.conf
I am stuck with max resolution of 1360x768
Any ideas how to get higher resolution?