I don’t yet understand why but if I login to Cups when it asks for authentication with the user as “root” & password it works perfectly. As my user name it doesn’t. I have sudo rights so don’t quiet understand it.
I’m not quite sure what’s changed but I must have done something. If I ever get to the root (sorry) of it I will post what I find.
I now completely trust driver less IPP printing. As such I have absolutely no installed printers in cups and my printers front-end in settings shows nothing when wifi printers are turned off. When turning any printer on, the system detects it automatically and I can easily send print instructions. However, page data loading takes a bit more time than if I did the same from my Android phone. Hope this helps.