Second monitor
I want to connect my iMac 2017 to my iMac 2021 to use as a second monitor. What cables to I need to do this?
iMac 24″, macOS 13.6
Question marked as
The 2017 iMacs never supported Target Display Mode. They are also too old to act as AirPlay Receivers for AirPlay to Mac. Your 2021 iMac can't use any other iMac as a TDM display.
See the details of the sad news in:
Use your iMac as a display with target display mode - Apple Support
System requirements for Continuity features on Apple devices - Apple Support
You might be able to use a 2017 iMac as a second display using a third-party workaround product like Luna Display (Astropad), or Duet Display, perhaps in combination with a Thunderbolt 3 cable between the iMacs. But these have limitations compared to a real hardware monitor connection.
