Problem

I use a single wide-screen 4k monitor for my home office setup. My laptop lid remains closed and the laptop is plugged into a docking station the entire time.

However, after upgrading my MacBook to a 2023 MacBook Pro (Apple M2 Pro chip) I was unable to use my Dell S3422DW monitor, it was displaying the following error on the screen:

The current input timing is not supported by the monitor display. Change your input timing to 3440x1440, 60Hz.

With the laptop lid open I was able to change the Display settings using the laptop screen on the laptop and change the refresh rate to 50Hz after which the display started working. However when I closed the lid of the laptop it would revert back to the 60Hz setting and the external monitor would again not display.

Solution

To work around this issue I installed the screenresolution app e.g.:

brew install screenresolution

Then I was able to issue the following command before closing the lid and the display was set correctly:

sleep 6; screenresolution set 3440x1440x32@50

This setting survives across reboots and the issue is resolved.