When you mention you had success earlier with other systems - one point of difference could be if Gnome is using xorg vs. wayland - and if I recall correct - vnc does not work on wayland.
If your requirement is simple then connecting using VNC over SSH is a viable alternative but still you need to use xorg for the Gnome desktop.
Getting remote access to a Wayland powered Gnome - Projects/Mutter/RemoteDesktop - GNOME Wiki!