Where as the Mac Mini might be a well made a decent bit of kit, it is NOT a server. (Although apple price it like it is)
It reminds me of when I used to work for a local education authority around 15 years ago, we used to get schools going with cheaper quotes from other IT business for 'servers' for the school network than the ones we would provide.
When you went out an looked at what they had bought, they were just a PC in a tower case and often no better specs than the ones they had on the desks for the students to use, but with Windows server installed on it. And they wondered why they would begin to fail after a couple of years of being left running 24/7, right after any warranty they had with the original company had ran out.