I had the exact same problem but with a dell xps15 9550 with a thunderbolt to display port in MsT mode with 2 external screens. Afer Sergeys tips everything became stable and workable.
-- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1552040 Title: [Lenovo ThinkPad T440s] Laptop sometimes doesn't detect external monitor To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video-intel/+bug/1552040/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs