Using Late 2012 iMac as Second Monitor
I just upgraded to the iMac (Retina 5K, 27-inch, 2020), and would like to use my iMac (21.5-inch, Late 2012) as a second monitor. It worked great on my last 5K iMac, but it won't connect to my new one. I have them connected via an Apple Thunderbolt 2 cable, using an Apple Thunderbolt 3 adapter, but when I press "Command-F2," it doesn't work. Any ideas?
iMac 27″, macOS 10.15