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I use an external screen with my Intel MacBook Pro for work, as well as the built-in display. I keep both screens on when I'm working, and I put the laptop into sleep mode when I'm not using it.

However, I've noticed that in sleep mode, the MacBook keeps the external display on (displaying black, but still on).

The display is an LG UltraGear 32GN63T, connected via DisplayPort through a USB-C dock. I have used this dock on a Windows laptop, and it turns off the display correctly when the Windows laptop goes to sleep. So, this isn't a dock problem, at least.

Is there a fix for this? (keep the external display off when the MacBook is sleeping)

Specs:

  • MacBook Pro (15-inch, 2019, Intel)
  • MacOs Big Sur 11.7.1 (20G918)
  • LG UltraGear 32GN63T
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  • Are you sure it's the MacBook that is preventing the display from turning off? Does the display have a control panel menu where the delay is set?
    – benwiggy
    Commented Feb 24, 2023 at 18:00
  • @benwiggy it is not the MacBook, because I can shut down the MacBook and it lets the display turn off/go to sleep by itself like normal.
    – bigyihsuan
    Commented Feb 24, 2023 at 18:04
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    A dock is a very different animal. Keep in mind the Mac will keep power to USB-C ports to facilitate power nap activities (like writing TM backups to an external drive) so, the dock stays awake. Windows does this differently and puts the ports to sleep
    – Allan
    Commented Feb 24, 2023 at 18:12
  • Does the USBC Dock have its own power supply you keep connected?
    – IconDaemon
    Commented Feb 25, 2023 at 13:45

1 Answer 1

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I had the exact same problem with my LG 35wn75c. MacBook Pro connected via USB-C (DP alt mode), but no dock.

What fixed it for me was changing this setting Battery > Options > Wake for network access to Never (it was previously on "Only on power adapter").

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  • Thanks for the answer and Welcome to Ask Different. I am slightly confused by your use of DP Alt mode since my understanding is that Thunderbolt 3 encapsulates full DisplayPort and no USB-C alt mode is needed. Can you edit this if you know more or I’m incorrect? anandtech.com/show/15752/displayport-alt-mode-20-spec-released (Perhaps you mean your display lacks thunderbolt so you know the Mac has to enable the less capable alt mode?)
    – bmike
    Commented Nov 21, 2023 at 16:26

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