How do I enable 2560x1440 resolution for screen sharing virtual display on Mac Studio?

Hi,

I have an M4 Mac Studio which is connected to a display with resolution 2560x1440.

However, another use case involves me switching this display off and using Screen Sharing from a Macbook Pro to the Mac Studio. Or to be more accurate, the display has three inputs, so I will switch the input to the Macbook Pro, and then use Screen Sharing from the Macbook Pro to the Mac Studio.

So, to be clear, the Macbook Pro is now using the display, at 2560x1440, and I use Screen Sharing to connect to the Mac Studio.

The problem is that inside Screen Sharing, the Mac Studio does not support a resolution of 2560x1440. The main supported resolution inside Screen Sharing is, for some reason, 1920x1080. This is listed on System Settings -> Displays, when inside Screen Sharing on the Mac Studio - the device is called Screen Sharing Virtual Display. The resolutions supported include 3840x2160, 1920x1080, 1440x900 and several weirder ones like "2880x1800 (low resolution)", 1024x768, 800x600 and so on, for a total of 21 possible resolutions. However, 2560x1440 is not on the list!

Because I cannot choose 2560x1440, I can't utilise the full size of my display with Screen Sharing. At 1920x1080 resolution there are large black bars on each side of the screen, since 1920x1080 is obviously smaller than the native 2560x1440 of the display. If I choose 3840x2160, then I get a screen which is bigger than the display, so that I have to scroll around horizontally and vertically. Neither of these is a good solution - I need to be able to use 2560x1440 as the Screen Sharing resolution.

I installed a command line utility called "displayplacer" and checked the output of "displayplacer list". This is the exact same list I can see inside System Settings. The problem is that this list still does not contain 2560x1440 as a possible resolution.

I've tried with two different display cables for the Mac Studio; both have the same issue. The cables were HDMI -> HDMI and Thunderbolt -> HDMI. Both of these cables work fine when the Mac Studio is directly connected to the display, i.e. I can use the native resolution of 2560x1440, but both cables have the same issue of 2560x1440 not being supported when inside Screen Sharing.

I previously had a Mac Mini, an older model from 2018 with an Intel processor. With the old Mac Mini the scenario described here worked just fine, there were no issues - I was able to use 2560x1440 as the virtual resolution inside Screen Sharing. Just now with the new M4 Mac Studio I cannot use 2560x1440 inside Screen Sharing. With the old Mac Mini I used the same cables, the same display, the same everything, and it worked fine.

This issue seems to be specific to the Mac Studio then; somehow, specifically with the new M4 Mac Studio, it does not support the resolution I need with Screen Sharing Virtual Display.

[Re-Titled by Moderator]