HP Office Jet Pro 9015 Catalina Certificate Issue

I have been troubleshooting a printer for 2 weeks. It's a long story (https://h30434.www3.hp.com/t5/Printer-Setup-Software-Drivers/HP-Office-Jet-Pro-9015/td-p/7843924) so here goes:

I first ran into the Catalina HP Certificate issue on my own Macbook Pro running Catalina and an HP 1102W. This older printer uses a simple driver package so I was able to simply download the standalone driver update from HP (11/20) and boom, all good.

I was asked to service a Macbook Pro with the same error and an HP Officejet Pro 9015. I went to update the driver but it uses some HP App in the APP store and that's where the problem began. The malware warning wouldn't stop coming up no matter what I did. I eventually found a software package on HP that made that warning go away and installed the new framework.

But...when I go through printer setup I keep getting a network error of some kind. I have worked on the HP forum (https://h30434.www3.hp.com/t5/Printer-Setup-Software-Drivers/HP-Office-Jet-Pro-9015/td-p/7843924) to try to solve this, they've run me through a variety of solutions. The HP 9015 installs fine on my Macbook Pro on Catalina on the same network as the one I'm being asked to work. But there's something stopping the non working setup from seeing the printer. I have them side by side, I run through the same process on both computer, same network, etc. One can connect, the other cannot.

I tried both wireless (where my computer printed and the other didn't) and put the LAN cable back in and again, one installed fine, the other did not. Same network. Same OS. Same supplemental update. What am I missing?!

For 4 years the printer has worked fine with the printer on the LAN and the Macbook Pro connected on the wireless network. Now it can't connect during setup no matter what I do - produces some kind of a network error. I've detailed much of it on the HP forum, it's been a trying two weeks.

Are there some network settings I'm missing on the Macbook Pro that isn't connecting to the printer? Both are running Catalina 10.15.7 with the supplemental update.

If it were the network I'd assume both machines would be blocked and if it were repeaters / etc as they thought it was, it wouldn't have that issue when I plugged the LAN cable back in (we won't go there).

I'm desperate for someone to click over to the HP forum, review my thread and see if if they have any ideas. It's not a paid job, it's a favor, so I could really use some help here. I'll be back on site Friday.

There has to be some reason why, when both computers are on the network, one can see it and install / print fine and other other cannot. I tried to compare network settings screen-by-screen and it's just not obivious to me. I have graphics of what has happened: Without the thread they are slightly out of context but...many are side-by-side:

http://artistcreatives.com/printer.jpg

http://artistcreatives.com/wireless-network.jpg

http://lemurhost.com/media/IMG_7271.jpg

http://lemurhost.com/media/IMG_7275.jpg

http://lemurhost.com/media/IMG_7276.jpg

Admittedly I'm a Windows technician first, but I'm wondering if there's some setting, some checkbox, something that is blocking that printer on the Macbook Pro that isn't connected to. I even tried sharing the printer from a USB connected Mac Desktop and this computer can't connect.