Network problems with a MacMini 2018
Solution 1:
I finally found the culprit. It was due to the Anker USB hub I connect to the Mac Mini. As soon as I connect it, the Wifi stops working. Check out the issue on the Apple forum.
Connecting the hub to the back of the Mac mini killed all wifi connection immediately. Reading online I found what I thought would be a good solution. Turns out a USB extension cord might help. Create some distance between the Mac and the hub.
That's crazy!