Ubuntu 16.04 cannot connect to HP Officejet Pro 8620

I cannot connect to our HP Officejet Pro 8620 from my computer which is running Ubuntu 16.04. I can connect from another computer on the network which is also running Ubuntu 16.04.

I have tried re-installing HPLIP (latest version 3.17.11), rebooting my computer, restarting the printer, and using CUPS. All result in no connection.