When reestablishing the display connection on wakeup it's possible the machine doesn't think there's enough bandwidth for 4K, temporarily. This theory is also supported by the fact that lower bandwidth modes don't exhibit the bug.
Next I would suggest trying to replace the cable with one that's higher quality. ** Tags added: multimonitor noble ** Package changed: xorg (Ubuntu) => xorg-server (Ubuntu) -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/2066129 Title: The external monitor does not wake up from sleep at 4K resolution To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xorg-server/+bug/2066129/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
