Ethernet: problem connecting to printer

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Level 1

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Ethernet: problem connecting to printer

I have an elderly Mac Pro and an HP laser printer, both normally connected to a router via Ethernet. Everything has worked perfectly for years. However I have changed the router as part of a broadband upgrade, and the Mac Pro can no longer find the printer. I think this is due to the printer having a fixed IP address and the router being set up for DHCP.

So I have now plugged the printer directly into an Ethernet port on the Mac, but the Mac will still not connect. The Mac has been restarted; printer removed from the printer list, power cycled and re-added to the list. System Preferences > Network says the Ethernet connection is "Active", which I assume means the physical connection is OK.

What have I missed?

Mac Pro

Posted on Jun 26, 2020 9:48 AM

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Answer 1

Best reply

Camelot

Level 9

54,339 points

Jun 26, 2020 11:38 AM in response to John Sandell

If the printer has a fixed IP address then it still won't automatically connect, even if you run an ethernet cable directly between your Mac and your printer. You would have to manually configure your Mac to be on the same subnet as your printer - which might be OK once in a while, but would be a PITA long term.

The simplest solution would be to change the printer's configuration to use DHCP. That way it would get a dynamic IP address on your local network and would be available to any device on the network. The Mac's auto-discovery protocols mean that the Mac would still find the printer even if its IP addresses changes over time (which can happen with DHCP), but if that rarely happens unless the printer is turned off for an extended period of time. Even then, you may have options in your router to assign a specific IP address to your printer via DHCP.

Ultimately, DHCP solves most of the problems you're describing. You just need to reconfigure the printer to use it.

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Answer 2

John Sandell Author

Level 1

46 points

Jun 26, 2020 2:33 PM in response to Camelot

Thanks that's useful. In fact the main reason for trying to connect the printer direct to the Mac (apart from needing to print something now) was to be able to get into the printer to change it to use DHCP. But until I can talk to the printer I can't change its configuration. It's had a fixed IP address for many years now and I can't remember why it was set that way, though it connected well with the old router.

Can I ask how difficult it would it be to set up the Mac to be on the same subnet as the printer?

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Answer 3

BobHarris

Level 9

53,291 points

Jun 26, 2020 4:13 PM in response to John Sandell

Not all routers use the same subnet. So if your printer is on 192.168.0.nnn, and your new router uses 192.168.1.*, the router would not pass any traffic to the printer.

And if your old router was an Apple Airport Extreme or Time Capsule, then it was using 10.0.1.* as its subnet, most non-Apple routers use 192.168.*.* address rangers for their subnet.

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Answer 4

John Sandell Author

Level 1

46 points

Jun 28, 2020 3:14 AM in response to Camelot

Have now set up one Ethernet port to be on the same subnet as printer, and am communicating with it, so I can go on from there. Many thanks for the pointer.

AAMOI I've found the manual for the printer, which recommends fixed IP: "DHCP-supplied addresses are dynamic and might cause problems for computers and printers, which expect IP addresses to be static... HP recommends configuring the print server with a static IP address." ["print server" is what HP calls the Ethernet dongle that plugs into the printer's interface socket].

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Answer 5

Camelot

Level 9

54,339 points

Jun 30, 2020 11:23 AM in response to John Sandell

> I've found the manual for the printer, which recommends fixed IP

If it's really old, the printer might predate modern (e.g. <5 year) auto discovery protocols.

Historically IP printers, especially those in Windows-based networks preferred (required?) static IP addresses because they used a print server to share the resource and the print server would choke if the IP address of the printer changed (or all the clients would have to be updated to reflect the new address. This make moves and network changes hard, and helped a good number of IT support professionals stay fully employed for years.

That all started to change about 8-10 years ago with the uptick in systems like Rendezvous and Bonjour for service auto-discovery to help address this problem, and in more recent years things like AirPrint have elevated it further. Suffice to say, most modern printers don't have the same issues any more.

Glad you got it working, though.

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Answer 6

John Sandell Author

Level 1

46 points

Jul 1, 2020 2:08 AM in response to Camelot

Interesting, thanks.

> If it's really old...

It is really old :-) Date Manufactured = 01/2003 according to the test page. Still prints well though paper handling is poor. It replaced an Apple LaserWriter purchased for a lot of money in 1987.

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