allow-tcp

Ubuntu 22.04

Xubuntu uses lightdm; Kubuntu uses sddm.

Lightdm

Edit /etc/lightdm/lightdm.conf

[Seat:*]
xserver-allow-tcp=true
autologin-guest=false
autologin-user=john
autologin-user-timeout=0

sddm

Edit /etc/sddm.conf

[X11]
ServerArguments=-listen tcp