"Hold for Authentication" When Trying to Print

I have a small business office with a handful of Macs and a handful of shared Brother printers - some wireless, some USB connected to the closest Mac and shared on the network from that computer. This setup has been unchanged and working for years, when seemingly out of the blue, our Brother HL-2240 USB (basic no frills B&W laser printer) is no longer able to be used by other computers on the network. It prints fine via USB, is visible over the network and can be added as a new printer over the network, but any print job sent to it from a network computer displays the error in Print Center: "Hold for Authentication", although there's nowhere to enter any type of authentication or any indication whose authentication would be required. Other wireless printers and USB printers shared on the network continue to work fine and other wireless traffic including screen/file sharing work fine.

What is going on? Is it the printer? The computer? The network? Some mangled combination?

Nothing I've tried has worked:

• Remove and re-add the printer from the client computer.
• Remove and re-add the printer on the host computer.
• General Printer sharing is enabled on host computer.
• Sharing is enabled for this printer on host computer, "Anyone can print" selected.
• Plugged printer directly into client computer (it worked fine over USB), shared it, and previous host computer had the same "Hold for Authentication" error.
• Factory reset the printer.

Hardware involved:

Printer: Brother HL-2240 USB

Host Computer: Mac mini 2018 w/ macOS Sonoma (14.7.1)

Client computer: Mac mini 2018 w/ macOS Sequoia (15.2)

Network Access Point: TP-Link EAP610

Network Firewall/Router: SonicWall TZ 270