Connecting Mini to 2014 iMac

Target display mode is a feature that was available only with certain older iMac models.

The feature has been deprecated by Apple and is no longer supported in hardware or software.

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

Only the following older iMac models could be used as an external display when plugged into another older Mac model:

• iMac models introduced in 2011, 2012, 2013, and mid 2014 using Thunderbolt or Thunderbolt 2 cable.
• 24-inch and 27-inch iMac models introduced in 2009 and 2010 using Mini DisplayPort cable.

• The intended target iMac must be running macOS 10.13 High Sierra or earlier; it does not work with macOS 10.14 Mojave or later, or with Boot Camp and Windows.
• Retina display iMacs won’t work as target displays.
• In all cases the source Mac that you're connecting FROM must have been introduced in 2019 or earlier and have macOS 10.15 Catalina or earlier installed.

If the 2014 iMac will not boot properly into the normal User Login screen or into Target Disk mode or into Safe mode, then making any sort of connection to your new mini will not be possible. The computer must be working in order to use it.

If using wi-fi keyboard or mouse with the mini and things aren't working, try using a wired USB keyboard and mouse. TIP - it's always a good idea to keep a USB keyboard and mouse handy for fixing problems like this.

If you are using the newer rechargeable Apple Magic Keyboard, you can plug it into the computer with its Lightning charge cable and it will function as a wired keyboard.

What year is the Mini?