I have a bit of an odd issue with my 2020 MacBook Air (M1) and Dell U4021QW monitor.

When the Mac goes to sleep whilst connected to the monitor, the monitor doesn't go into standby. The screen is dark, as in nothing is being displayed, but the monitor is not sleeping, it's still still on just not having a signal.

My work Mac is an older intel MacBook Pro, when connected through the same thunderbolt port in the monitor (and cable) it doesn't have this issue, when the laptop goes to sleep, the Dell monitor goes into standby as expected. I get similar results on my PC workstation, which is connected to monitor via DP.

I checked the battery section on both Macs, and all seems similar.

Anybody have any clues how to proceed troubleshooting this?

  • Curious if you ever found a resolution to this? I'm encountering the exact same issue with a M1 MacBook Pro and the Dell U4021QW. Latest firmware on the monitor didn't resolve anything and I'm macOS Ventura 13.0.
    – Rob Lauer
    Commented Oct 29, 2022 at 18:17
  • I'm afraid not. Problem persists.
    – JustDanyul
    Commented Nov 13, 2022 at 14:07

2 Answers 2


Did you update to the latest firmware? The latest has a June 2022 release date, referencing a fix to the "Macbook M1 issue":


  • im afraid i am on the latest firmware. So, i expect its another issue they were referring to.
    – JustDanyul
    Commented Nov 13, 2022 at 14:06

FWIW, my U4021QW monitor had a dead bright pixel so I got a replacement under warranty. I don't know if the new one I was sent is a newer rev of the monitor, has a newer FW version (M2T104), or I missed a setting before (see below), but now when I put my Mac to sleep (in clamshell mode), the monitor will wake after I hit the keyboard a few times.

enter image description here

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