Second monitor problems with Monterey
I've got an iMac running on Monterey 12.3.1 and want to use my old iMac (mid 2014) as a second monitor. It appears this is impossible even though I have them linked up with a lightning cable and adaptor. Is there any way I can achieve this? I don't want to screen mirror, I want to use the old iMac as an extended desktop. Having two monitors is essential for work, I'm starting to wish I hadn't bought a new iMac and gone with a Windows system