MIME, thank you for reporting this and helping make Ubuntu better. To reduce this down to to a simple test case, and make it easy to debug, let the focus be on only the following setup: Lenovo X250 connected directly via Mini DisplayPort to Dell P2415Q
With this in mind: + What is the largest working resolution? + What is the least big non-working resolution? + After attempting to use the monitor on the least big non-working resolution, please attach both of the following uncompressed/untarred: Xorg.0.log Xorg.0.log.old ** Changed in: xorg (Ubuntu) Importance: Undecided => Medium ** Changed in: xorg (Ubuntu) Status: New => Incomplete -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1547043 Title: 4k Support not working To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xorg/+bug/1547043/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs