From #10, it still looks like CUPS is sending a printer URI of "http://192.168.1.7:631/Stylus_Photo" to the NAS for some reason - but only for the Get_Printer_Attributes call, *not* for Print_Job! If this were not true, we should be seeing "print_job: resource name '/Stylus_Photo' no good!" in your NAS logs too, and that isn't there.
From #10, it still looks like CUPS is sending a printer URI of "http:// 192.168. 1.7:631/ Stylus_ Photo" to the NAS for some reason - but only for the Get_Printer_ Attributes call, *not* for Print_Job! If this were not true, we should be seeing "print_job: resource name '/Stylus_Photo' no good!" in your NAS logs too, and that isn't there.