Mobile Printing & Cloud Printing

My HP Officejet 8260 has Instant Ink cartridges as I am subscribed to the service and for it to print it needs to be connected to Web Services, so that Instant Ink can track number of pages printed to appropriately bill based on subscribed plan.  Recently, my printer had stopped printing because it was unable to connect to the Internet, so I carried out a number of tests and even posted the issue on my ISP community forum for help (Virgin Media) who have been extremely helpful.

• The printer successfully connects to the ISP router (SuperHub 3) using both Wired Ethernet and over WiFi and shows me the IP address assigned by DHCP, gateway being the IP of my router and the subnet address.
• I can even successfully communicate with the printer using the printer software on my PC over the LAN, e.g. I can scan a document to my PC.

Having established the fact that there is no LAN connectivity issues lets talk about the problem: 

Problem

• I am unable to print anything even a test page because the printer prompts me that I need to be connected to web services (HP Connected/Instant Ink) - asks do you want to connect?
• Proceed with selection of 'Yes' and get an error: Unable to connect to the Internet check if there is a proxy or contact ISP administrator - why is it not able to connect to the internet when there is no change?
• I have taken the route of discussing this problem with my ISP having led to believe that the fault lies there, and was advised to test the printer over a mobile hotspot to rule out my ISP.  I did this and observed the same problem over my mobile provider (EE) hotspot, confirming the issue lies in the printer firmware or at the HP connected web service.
• I need help from HP can you please advise me the best way forward.
• I want to know if there has been a roll-out of printer firmware - how can I determine the firmware of my printer? Can I roll back to a previous version?  If it's not the printer firmware then it is the target Web Service that it is trying to connect to that is not reachable.

Please do not advise me to carry out the usual steps as I've done them all and none have worked:

1. Carried out disconnecting power supply and holding the power button for 15-30 secs
2. Carried out reset setting to default
3. Carried out a fully factory reset and setup
4. Checked for printer software update, informs me I have the latest software

Something in the printer or at HP web service has changed so it is HP's responsibility to assist, identify the root cause and provide resolution.  The printer has been deemed useless or at least with the Instant Ink service.