This post is not asking for help. I just want to share a solution that I found to a problem that I was having with remote printing between Zorin 16 Pro computers and also between Zorin 16 Pro and other Linux distros.
My main computer is a 2018 iMac running Zorin 16.3 Pro. I have an Epson printer connected to it via USB and local printing was working fine. I also have a bunch of laptops (Macbook Pro(Zorin), Macbook Air(Zorin), System76(Mint), Dell(Untramarine) & Mackbook Air(OSX). I couldn't get remote printing to work with any of the laptop. I followed all the publish guidelines, set all appropriate flags to share etc etc etc. Nothing worked. Then I found a comment in a Troubleshooting section on a Ubuntu form and it suggested that I run the following command on all computers, and it worked!!!!
Here is the command:
"sudo iptables -A INPUT -p tcp --dport 631 -j ACCEPT"
I was so relieved when I got this working. I hope this helps someone in the future that has the same problem.
EDIT: I'll leave the above because it may be useful. But I've learnt since posting this, that I didn't have it fully fixed, but all I really needed to do was allow port 631 in UFW.
Regards ... Tim, Hasting Minnesota.