Screen sharing between two iMacs (mini display/catalina to thunderbolt/big sur)

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hwrite1947 Author

Level 1

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Screen sharing between two iMacs (mini display/catalina to thunderbolt/big sur)

Main iMac - 2021 version with Big Sur - with thunderbolt 3 ports.

Spare for sharing iMac - 2103 with Catalina 10.15.7 with mini display ports

I've connected miniport to thunderbolt 3 ports and tried pressing Cmd F2 with no result

If I go through finder and select screen share I get the following error

If I visit the VNC then I can access the other screen but I really just want the spare iMac to be an extension to my main Mac screen.

I run Bitdefender but don't have firewall so feel maybe its the connection mini display to thunderbolt

Has anyone successfully managed to do this?

thanks

Posted on Apr 27, 2021 11:52 PM

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Jack-19

Level 8

46,116 points

Apr 27, 2021 11:55 PM in response to hwrite1947

Hi hwrite1947,

First, delete Bitdefender! It is junk for Macs.

Secondly, if you want a "dual" display setup with Target Display Mode, then sorry, but it is not compatible with your 2020 iMac, macOS Big Sur, and macOS Catalina. So, nothing really works. You need to buy a standalone external display, such as one form LG or HP.

Cheers,

Jack