Our office printer, a Konica Minolta Bizhub multifunction, is connected to our network via an old Cat 5 (not Cat 5e) Ethernet run, so it only auto-negotiates to 100mbit rather than gigabit. No real problem there and it’s worked fine for months. The other day while fishing around for another network jack behind some bookshelves, I yanked around the wire to the printer jack (which is just in a plastic box sitting on the floor, not in a proper wall box or anything). After that the printer would still print, but I couldn’t access its web interface and scan-to-email would timeout. It’s like it was dropping upstream packets but downstream was still ok.
So I opened up the box with the jack and all the wires seemed fine, and I traced the run through the basement to our Ubiquiti switch, and it all looked ok there too, if a bit tightly secured in places. Swapping the patch cable did nothing, changing ports on our switch did nothing, unplugging the printer from power for a hard reboot did nothing. So I got a long patch cable and plugged it into another known good jack and it worked fine. Ok so the wiring is definitely suspect. However, after plugging it back into the old jack with the iffy wiring it now works fine again. What? I can’t come up with an explanation for that. We do have a DHCP network but the printer has a static IP in a different address range so it shouldn’t be an addressing issue. Maybe something related to the auto-negotiation in the printer’s Ethernet card that was kicked in the pants by giving it a good connection? Any ideas?