Switch from Wayland to Xorg in Ubuntu

echo $XDG_SESSION_TYPE

edit /etc/gdm3/custom.conf and uncomment the line:

#WaylandEnable=false

sudo apt-get install xserver-xorg-video-dummy

Then write it in the /usr/share/X11/xorg.conf.d/xorg.conf (or possibly /etc/X11/xorg.conf) file (create one, if it does not exist):

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 "1024x800"
    EndSubSection
EndSection



After this the connected display will not work, to fallback

sudo mv /usr/share/X11/xorg.conf.d/xorg.conf /usr/share/X11/xorg.conf.d/xorg.conf.bak

sudo mv /usr/share/X11/xorg.conf.d/xorg.conf.bak /usr/share/X11/xorg.conf.d/xorg.conf