Thank you for that link, I've google many how to upgrades.
It's interesting that links shows a SAMSUNG drive should work.
The issue I'm struggling with is, I'm not sure the system supports two SSDs at the same time.
The 2014 Mac Mini has a 256GB PCIE SSD as the main boot drive.
There is room for a second 2.5" drive in the second bay, when I install the SAMSUNG there it won't format and the 4TB size isn't recognized properly. It reports as 2.2* (with an asterisk).
I think I'll try a Crucial SSD next as the link you posted has led me to also find other recommendations that the Crucial may work.
I'm really trying to find someone that has done it and said "yes that works".
I'll try a Crucial next.