I found a solution, posted this on a few other forums today, doing the same here
I had this same problem occur on 3 printers, all different models, different release years, different firmware (FutureSmart 3.x and 4.x). Was working one day, next day I get some form of error and never worked again even after resets, FW upgrade, removing devices from hpconnected and readding. Banged my head a few hours before I discovered a simple fix through hours of trial and error...
Error Messages Returned:
Could not communicate with HPconnected.com
Unable to contact HP Connected. ePrint service may be affected
Steps to Resolve:
From the device EWS, the following steps...
-Login as user Administrator (admin)
-Go to tab HP Web Services
-Left nav select Web Proxy
-Proxy Server port was set to 80; change to 8080
-Reattempt--> from left nav select Web Services Setup, enable.
-Impact of change---> It worked, but I could no longer use the custom ePrint Address I had defined, and had to create a new one and tell my user base of the change