For me, updating drivers solved the issue. I have got Intel controller: $ lspci | grep VGA
00:02.0 VGA compatible controller: Intel Corporation HD Graphics 620 (rev 02) This is how to update drivers: sudo add-apt-repository ppa:oibaf/graphics-drivers sudo apt-get install xserver-xorg-video-intel hope this helps. -- 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/xorg-server/+bug/1771185/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs