CUPS and IPP strangeness

I'm managing a small network with about a dozen printers. Some are
unable to accept IPP and are configured to use JetDirect. All others
are configured with IPP.

But one JetDirect printer in particular is having some strangeness.
The /etc/cups/printers.conf file contains these lines.

  <Printer PF0>
  Info HP p2055dn
  DeviceURI socket://pf0

But /var/log/cups/error_log contains lines like this one (wrapped here).

  E [29/Jul/2025:22:03:18 -0700] Returning IPP client-error-bad-request
  for Send-Document (ipp://localhost:631/printers/PF0) from localhost

That sure look to me like CUPS is trying to send IPP traffic to this
printer. That certainly won't work, port 631 is not open on this printer.
I've restarted CUPS without effect. What can I do to fix this?

My major task on this network is to port it to a new system running a
much more recent OS. At this time, CUPS is running on CentOS 6 and is
version cups-1.4.2-81.el6_10.x86_64. I need to keep it running awhile
longer.
-- 
         Dave Close, Compata, Irvine CA       +1 714 434 7359
       [email protected]              [email protected]
  "One thing a person cannot do, no matter how rigorous his analysis
   or heroic his imagination, is to draw up a list of things
   that would never occur to him." -- Thomas Schelling