I got a new printer. Auto-discovered, added, and prints fine from Windows in 2 minutes. Auto discovered, added, and prints fine from OSX in 30 seconds. Auto-discovered and added on Linux, but trying to print results in "printer is unreachable at this time" - even after 50 re-installs, different configs, different drivers, different protocols.
I recognized that some computers were on different subnets, but couldn't figure out a pattern. It turns out that the printer has a setting called "Restricted Server List" and the default setting is null. Here's its description in the admin interface: "Comma-delimited list of IP addresses that are allowed to make TCP connections. Example: 157.184.0.0/24. where 0 is a wildcard and /24 is the network prefix."
It also has a setting called "Restricted Server List Options", set to block all ports by default. Here's its description: "By default, addresses not in the restricted server list will have all access blocked. When Block Printing Only is selected, addresses not in the restricted sever list will be blocked from printing only. When Block Printing and HTTP Only is selected, addresses not in the restricted server list will be blocked from printing and HTTP. "
Admin interface doesn't say this anywhere, but the default setting of no restricted servers apparently allows access from other networks, but not from the same network as the printer. I set the restricted servers to "192.168.132.0/24" and then I could access the printer admin web page and print to the printer from my Linux box, but not from any of the computers that were working before. So I set it to "192.168.0.0/16" and every computer on all subnets in my house can print and access the printer admin.
The default setting of no restricted servers was extremely non-intuitive in that it actually only restricted servers on the same subnet. And there was no such documentation.
What a crappy waste of 7 frickin' hours!
With gratis Linux we pay with our time. You did very good to go through all this hell in a mere 7 hours. Programmer creating those monstrosities don't understand our mundane concerns.
P.S. : still Linux has qualities that makes it superior in many ways.
The problem as described has nothing to do with Linux.
It was a default printer setting that blocked access from all computers in the same network.
Honestly, this is a pretty good example of why this isn't an inherent Linux problem. It's a problem of using any OS that isn't popular enough to be supported by manufacturers. More people using Linux would cause problems like this to stop happening.
I realize that's a distinction without a difference to a lot of people, and that's totally okay. I'm not saying that's wrong, but it matters to me that the benefits of Linux are specific to the OS, while most of the problems are not.
None of this has anything to do with the operating system of the devices trying to use the printer.