Connecting a 2023 Apple Macbook Pro M2 16" to a 2017 27" iMac

Those Mac's are not supported by Target Display Mode over a wired Thunderbolt connection.

carefully read > Use your iMac as a display with target display mode - Apple Support

You will have to use AirPlay or a third party screen app like LunaDisplay.

Use your iMac as a display with target display mode - Apple Support

https://astropad.com/product/lunadisplay/

Pawbear56 wrote:

Help! I have just purchased the Apple Thunderbolt 4 (1.8m) cable to try and connect my Apple Macbook Pro M2 2023 16" to my 2017 27" iMac with retina display.

After connecting the cable to both Thunderbolt ports using the Thunderbolt 4 cable, I the Macbook will connect to the iMac, but the display from the iMac is on the Macbook Pro - I want it the other way round, so the display on the Macbook pro is on the larger 27" iMac.

I have checked the specifications and is should work, but it's not at present.

Target Display Mode was never supported on any of those Macs (individually, or combined), so I'm not sure what specification you read – or what you were doing to get the MBP to act as a second display for the iMac.

Unless, perhaps, you were using IP-over-Thunderbolt (Thunderbolt Bridge), with one Mac sending its video over AirPlay, and the other acting as an AirPlay receiver. Your M2 MBP is in the "works best with" list for the AirPlay to Mac feature, and your 2017 iMac isn't. So going by the support articles, AirPlay from the iMac to the MBP (MBP acting as AirPlay display) might work "at a lower video resolution", while AirPlay from the MBP to the iMac might not be supported (either because of the age of the iMac, or because you were running a pre-Monterey OS).

Set up your Mac to be an AirPlay Receiver - Apple Support

System requirements for Continuity on Mac, iPhone, iPad, and Apple Watch - Apple Support

how exactly did you get the iMac and MacBook connected? I’ve been trying and trying and trying and they don’t recognize each other in the displays menu

Cschwaherr,

In this case your suggestion will not work as the OP is attempting to use Target Display Mode which has been dead for many years now. If the OP was using an external display your suggestion would be valid.

Within the display setting menu, there should be an option to rearrange displays and click which one you want to be used as the main display.

Oh got it, thanks. I didn’t see the OP mention target display so didn’t know.