We have a fairly extensive campus network consisting of multiple subnets connected by a core router.
Everything has been working fine for years, but recently I have a number of macosx clients that refuse to print to a network printer (LPR) on a different subnet than the client machine. This is causing some consternation.
- Correct addressing, subnet mask, and routing has been confirmed on both the client machines and affected printers
- YES - I can ping the LPR printer via IP address from the client machine
- YES - I can ping the LPR printer via its DNS name from the client machine
- YES - I can telnet to port 515 on the printer from the client machine
- macOS "Network Utility" port scan shows TCP port 515 "open" on the printer from the client machine
- YES - I can pull up the printer's admin web page from a browser on the client machine
- I have tried removing and re-installing the printer on the client machine via both DNS name and IP addresss
- I AM able to print from the same subnet as the printer with no configuration changes
- I have tried both "dscacheutil -flushdns" and "sudo dscacheutil -flushdns" to no avail
The odd thing is, I have multiple macosx clients that will no longer print. More than one printer is affected, too.
If I connect a client machine directly to the same subnet as the printer (via Ethernet cable or WiFi), I can print just fine.
If I attempt to print to the printer from a different subnet, the PrinterProxy (macosx print monitor) app opens up and shows the document with the status below: "Printing - Connecting to printer." After some time it says "Printing - The printer is not responding."
- Client machine running macOS Sierra 10.12.6
- Konica-Minolta C652DS multifunction copy machine
- HP LaserJet 2100
This is baffling me. Clearly there is connectivity from the client machine to the printer. I have tried removing the printer and re-adding it via its DNS name and via its IP address. The same failure occurs in all cases.
My experience suggests to me that nothing is wrong with the printer or the network itself. It must be some bug in macosx or CUPS that refuses to talk to the printer if it's not on the same subnet.
Has anyone observed this phenomenon, and are there any solutions or suggestions?