The following bug has been logged on the website:
Bug reference: 16151
Logged by: paul van der meij
Email address: phjvdmeij(at)gmail(dot)com
PostgreSQL version: 12.1
Operating system: fedora 31
Description:
after startup of fedora, communication with postgresql from a client is not
working.
a 'systemctl stop postgresql' en 'systemctl start postgresql' solves the
problem
in the startup script /usr/lib/systemd/system/postgresql.service:
'network.target' should be 'network-online.target'
this solves the problem