I installed the gdm3 (3.26.1-3ubuntu3) and gnome-session (3.26.1-0ubuntu6) packages from artful-proposed.
I tried enabling and disabling Wayland in /etc/gdm3/custom.conf and rebooting with different sessions (Ubuntu, Ubuntu on Xorg, GNOME, GNOME on Xorg). Every time I logged in after reboot I got the session I expected based on my previous login and whether Wayland was available.
I installed the gdm3 (3.26.1-3ubuntu3) and gnome-session (3.26.1-0ubuntu6) packages from artful-proposed.
I tried enabling and disabling Wayland in /etc/gdm3/ custom. conf and rebooting with different sessions (Ubuntu, Ubuntu on Xorg, GNOME, GNOME on Xorg). Every time I logged in after reboot I got the session I expected based on my previous login and whether Wayland was available.