Well it works now, and the problem was a corrupted firewalld configuration.
The hint was when I tried the brute force approach of
telnet server.localdomain 631
and got "No route to host" indicating that the host resolution was working
but the port was blocked on the server.
One clean up and full reconfiguration of firewalld later, it's working.
The older print server (with iptables) was easier to troubleshoot
as I could just let everything pass through for testing.
My error in testing here was that "systemctl stop firewalld.service"
doesn't remove the firewall setup (like "iptables stop" would have).
Thanks to all who suggested various approaches, it did help narrow it down.
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