I renewed my printer (after a laudable 10 years using the old one) with a HP Envy 5546 and installation was a breeze. A week later suddenly no printer connection from my Mac. Despite reinstalling the wireless printer and trying to reset the printer in system preferences I was getting nowhere. My mac would not allow me to download the printer software. After a bit of hair-tearing I checked my wifi connection (Airport Extreme) on the Mac and, guess what, for some reason my mac had changed its access from my main wifi access to the guest access that I have enabled for visitors. Restoring the mac back to the main router access solved all my problems. Just shows that checking the simple things first pays dividends !