I have a Dell XPS-15 9570 and I am also affected by this bug. I am currently running 18.10.
The external monitor does not work with HDMI at all - when I plug it in to the machine, the monitor switches to low power mode. The same monitor is working fine over HDMI with a Dell M3800 running 16.04 -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1771185 Title: Secondary monitor not connecting in 18.04 LTS To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/libxrandr/+bug/1771185/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs