Airport doesn't see networked printers, internet access OK

Hello, all:

We are using the original Airport base station (round "UFO"-type), now at least 6-7 years old, mounted on a ceiling hallway. Never a problem until yesterday...

Internet access is fine but neither of our two networked printers are seen (HP 2055DN and Officejet 7650 AIO) by the daughter's iMac or the wife's iPad (running Printopia on iPad). I cannot add them back through the usual printer setup in System Preferences. Both are Bonjour compatible but aren't "seen" by the AIrport base station. Other ethernet-connected computers in the house (Mac Pro and Mini) work fine and can also see the base station via the setup utility. No system updates or changes have been made that I am aware of...

What I've done so far:

1. turn off everything, including the network switch and rebooted - no change

2. reset Airport and created a new home network - the new network was immediately accepted by the iPad and iMac and again, internet access was fine but no printers found

3. Checked the router settings - nothing changed there ( didn't think that would be a cause, but I was hoping...)

Summary:

Loss of networked printer access via Airport.

Suggestions gladly accepted! Something with network ID settings? Could our old Airport be dying? (I would have thought it would work or not work, not sort of work).

KWO