I did about the same thing yesterday on a very similar config and it worked. I remember i had to restart the computer after installation in order to get it work normally. Just to be sure, did you also tried to restart the Mac mini ?
I actually rebooted the server several times. Didn't help. Finally had to re-install 14.0.2.
Thanks. On the link, someone posted that the a new 14.0.4 install fixed everything and the FileMaker updated the FDS FMS download to 220.127.116.112. So I downloaded this, uninstalled the old, installed 18.104.22.1682 and everything is working.
Thanks for the pointer.