it works with wayland, this is a known limitation of the modesetting driver and is being fixed upstream:
https://bugs.freedesktop.org/show_bug.cgi?id=102508 ** Bug watch added: freedesktop.org Bugzilla #102508 https://bugs.freedesktop.org/show_bug.cgi?id=102508 -- You received this bug notification because you are a member of Ubuntu-X, which is subscribed to xorg-server in Ubuntu. https://bugs.launchpad.net/bugs/1776260 Title: Can't use three monitors properly; "xrandr: screen cannot be larger than 8192x8192" To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/mutter/+bug/1776260/+subscriptions _______________________________________________ Mailing list: https://launchpad.net/~ubuntu-x-swat Post to : ubuntu-x-swat@lists.launchpad.net Unsubscribe : https://launchpad.net/~ubuntu-x-swat More help : https://help.launchpad.net/ListHelp