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If you’ve have problems with external monitors not working on your Mac after upgrading to macOS Monterey, here we show you how to get them working again.

Many users have found that after upgrading to Monterey from Big Sur, one or more of the external monitors they were using suddenly stopped working with their MacBook Pro and Mac Mini.

This problem has affected both Intel Macs and the latest M1 Macs including the M1 MacBook Pro and Mac Studio.

The problem has also affected all brands of monitor including LG, Dell, BenQ, Asus, Acer and Xiaomi.

Some monitors are completely blacked-out in and not even charging the MacBook Pro connected by Thunderbolt cables.

Others are experiencing temporary black-outs which come and go or flickering.

This seems to have been a problem from the release of Monterey and although the 12.1 and 12.2 updates have fixed it for some users, many still don’t work.

The latest Monterey 12.3 update which was rolled-out for the release of the Mac Studio and Studio Display has also caused some external displays to stop working.

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Although there’s no one fix-all solution for every monitor the following solutions have worked for some monitors.

1. Change The Refresh Rate

For some reason the refresh rate of some external monitors has been affected by Monterey.

It seems that in some cases Monterey is trying to run external displays at a refresh rate that they’re not capable of.

The best monitors for Mac usually run at around 60Hz although some gaming monitors can run at over 100Hz.

To change the refresh rate, you need to go to the Display settings on your Mac by going to System Preferences > Displays where you can manually change the refresh rate.

We recommend setting it at 60Hz if possible but you can try experimenting with whatever options are available to see if it helps.

If you can’t see the refresh rate in settings, then try changing the resolution settings from “Default For Display” to “Scaled”.

You should then be able to see the refresh rate and change it manually.

monterey external display issues

2. Deactivate TrueTone

Some users have found that deactivating True Tone on the MacBook Pro display has helped to make external monitors work again with their Mac.

This is mainly on LG 4K or 5K UltraFine displays that support extending True Tone to them from your Mac.

On MacBook Pros and iMacs that support True Tone, go to the Display settings and you simply uncheck the True Tone box to deactivate it.

mac external monitor issues true tone

3. Use The DisplayPort Setting

In LG monitors, if you go into the Settings > General you may can select DisplayPort version to get it working again.

The DisplayPort version is usually set to 1.4 but if you change it to 1.2, you may find that the monitor starts working again with your Mac.

4. Use The HDMI Port

If you’re not having any luck with the USB-C or Thunderbolt port on your monitor, then you can try using the HDMI port instead.

If the Monterey problem is related to the USB-C or Thunderbolt connections ports, then no other workaround will fix it.

Note this may not work via a Thunderbolt hub. You’ll need to connect the HDMI to your Thunderbolt port using an HDMI to Thunderbolt adapter.

5. Disconnect & Reconnect Your Hub

If you’re using a USB-C or Thunderbolt hub to connect your monitors to your Mac, unplug and disconnect the hub and then reconnect it again.

The most reliable hub to use with an external monitor connected to Macs is the Apple USB-C Digital AV Multiport adapter.

6. Try Using SwitchResX

external monitor issues mac

SwitchResX is a simple app that allows you to instantly switch resolution on your Mac screen or any external monitors connected to it.

By experimenting with the resolution settings, you may be able to get your external monitors working again.

SwitchResX has been updated to work with the M1 chip too and allows you to change the resolution of your external monitors, set display rotation, set display underscan and more.

7. Change Thunderbolt Cable

In some cases, simply changing the Thunderbolt cable or HDMI cable will fix the problem.

If you’re using a cheap Thunderbolt or HDMI cable, we recommend buying an official Apple Thunderbolt cable or a high end HDMI cable such as the JSAUX HDMI cable.

8. Deactivate Nightshift

external display issues mac - nightshift

Nightshift adjusts the colors on your Display to the warmer end of the color spectrum. However, deactivating it has fixed the Monterey monitor issues that some users have been having.

To deactivate Nightshift, go to System Preferences > Displays and then uncheck Nightshift.

9. User BetterDummy

BetterDummy is a cleaver utility that aims to improve the way external displays work with M1 Macs.

BetterDummy works by works by creating a virtual display in macOS and then mirroring that virtual display to help improve the quality of images when connecting M1 Macs to external displays.

This is mainly ti improve the results with cheap QHD or FHD monitors but is worth a go if you can’t get your M1 Mac monitor working with an external display in Monterey.

10. Reset External Display

Sometimes when you change the resolution or refresh rate settings, your external monitor may not support the setting you’ve selected and go black.

In some cases, the monitor will reset itself back to a supported resolution or refresh rate but sometimes you’ll have to reset the external monitor manually to get it working again.

Note that resetting the NVRAM doesn’t usually fix this issue as it’s specific to the display settings on your Mac.

You can find full instructions how to reset an external display here.

If all else fails, it’s definitely worth contacting the manufacturer of your external display to see whether there is a firmware upgrade or known solution to the problem with Monterey and external displays.

Most manufacturers are aware of the problem by now and many will roll out fixes or suggest solutions specific to their models.

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