Hama hub hdmi problems

For some reason it happen to me once in a while that second monitor does not wake up on mac mini 2018. However, having a cheap HDMI selector i just push button on this until it land again on the proper port and that solve the problem. In your case, unplugging and plugging back physically on the port of the mac is far less a good approach as you may end up damaging the port. I’d rather prefer to scrap a $50 hdmi selector (in my experience, i have replaced both selectors once every 2 years or so, one at a time).

What brand and model are the Displays..?

I'm asking to find out, if there is another connection besides HDMI that can be used for one or both displays.

To compare notes with you and lanstrad1. My 2018 Mac mini has a similar issue, except that it is the display on the HDMI port that fails to relight and not the display on the USB-C port.

To overcome part of the problem, I leave the 2018 Mac mini on 24-7 and only allow the displays to turn off after 10 minutes. I almost never Shutdown and only Restart when required to by an update. Your milage may very using manual computer sleep overnight from the drop-down menu. Sometimes both displays return from computer sleep and sometime only one display returns from computer sleep.

That doesn't answer the what brand and model displays you have.

I would plug one display into the HDMI port using an HDMI to HDMI cable.

I would plug the second display directly into the Mac mini using a USB-C to HDMI adapter.

Then I would plug that HAMA USB-C hub directly into the Mac mini's other USB-C ports.