On some Solaris 11 hosts lookupDefaultPrintService() returns null while lpstat -d reports an ipp printer.
lookupPrintServices(null, null) returns one service.
I have several identical Solaris 11 machines, all configured to use the same CUPS printer on a remote host.
I don't understand where configuration is stored on this system; /etc/cups/printers.conf is empty on the machines. lpstat reports the service, and it is default and active from the point of view of lpstat. Printer is visible from localhost:631 and may be used to print a test page etc. It was set as a default by a call "lpoptions -d printername".
Attempt to set the printer as a server default from WEB interface fails with a message to the effect of "you should access this page via certain URL not on your localhost".