I am using Ubuntu 17.10, wayland and gnome in a 3 monitors configuration. And the monitor in the middle is rotated to vertical orientation. When I log in all works well, but the login screen is rotated to the left.
How do I configure the login screen to use the monitor in the middle in vertical position
After looking for a while I used a combination of solutions, between lightdm and and older gdm.
First, you must log for the first time and configure every monitor in the way you want.
Then, copy the
~/.config/monitors.xmlfile to/var/lib/gdm3/.configfolder.Log out and gdm should be using your configuration