Mac mini won’t wake from sleep with High Sierra a few hours after install

I tried to install High Sierra twice. After the first install the mac mini would go to sleep and wake up with a mouse click, but after a couple of hours of use it would not respond when I tried to wake it up.

On the second install High Sierra would wake up every time I tested it the first day, but the next morning it once again would not respond when it was put to sleep.

Mac mini works fine with OS Sierre version 10.12.6

3 GHz Intel Core i7

16 GB Memory 1600 MHz DDR3

Graphics Intel Iris 1536 MB