The Printer That Forgot Its Subnet

Date: 2026-01-28 Issue: Printer visible but unreachable Root Cause: Power surge + static IP from 2019 Status: Awaiting physical access

The Setup

I was doing some maintenance on Sirius-Station, my wife’s laptop. She mentioned the printer hadn’t worked “for a while.” I figured it would be a quick CUPS fix. Driver reinstall. Maybe a queue flush.

Five hours later, I was still debugging.

The Symptoms

CUPS could see the printer. It showed up in the print dialog. Jobs went to the queue. CUPS said “Connected to printer.”

But nothing printed. Jobs sat there forever, eventually timing out.

lpstat -p
# printer Brother_HL-L3290CDW_series is idle

Idle. Sure. Let’s test.

lp -d Brother_HL-L3290CDW_series /etc/passwd
# request id is Brother_HL-L3290CDW_series-42

Watched the queue. “Processing.” “Connected to printer.” Then… nothing. For five minutes.

The Investigation

First, check if we can even reach the printer:

ping 192.168.0.104
# PING 192.168.0.104 (192.168.0.104) 56(84) bytes of data.
# --- 192.168.0.104 ping statistics ---
# 10 packets transmitted, 0 received, 100% packet loss

100% packet loss. The printer’s IP was 192.168.0.104, but the laptop was on 10.42.0.174.

Different subnets. No route between them.

But wait — how did CUPS even see the printer?

The mDNS Trick

avahi-browse -r _ipp._tcp
# + wlx5ce931608890 IPv4 Brother HL-L3290CDW series    Internet Printer    local
# = wlx5ce931608890 IPv4 Brother HL-L3290CDW series    Internet Printer    local
#    hostname = [BRW30C9AB1824C9.local]
#    address = [192.168.0.104]

The printer was broadcasting its presence via mDNS on the local network segment. mDNS broadcasts work at Layer 2 — they don’t care about IP subnets. The printer was physically connected to the same switch, so its mDNS announcements reached the laptop.

But IP routing happens at Layer 3. The laptop had no route to 192.168.0.x. Every packet destined for the printer went to the default gateway, which had no idea what to do with it.

The Archaeology

Why was the printer on 192.168.0.104 anyway?

That subnet hasn’t been used on this network since 2019. Before the router upgrade. Before the whole network was renumbered to 10.0.0.x.

The printer must have been configured with a static IP back then. It worked fine on DHCP for years. Then… a power surge. The surge knocked the printer’s network settings back to some factory or cached state, and it reverted to that old static IP.

Now it was on the same physical network, broadcasting “I’m here!” via mDNS, but completely unreachable via IP.

The Fix (Pending)

The printer needs physical access to fix:

Go to printer control panel
Navigate: Menu → Network → TCP/IP → Boot Method → DHCP
Printer restarts and gets a 10.42.0.x address
Update CUPS with the new IP

Then reconfigure CUPS:

lpadmin -p Brother_HL-L3290CDW_series -v "ipp://NEW_IP/ipp/print" -E

I’m 40 miles away from that printer right now. The fix will have to wait.

The Drivers (For Future Reference)

While I was there, I installed every Brother driver known to humanity:

hll3290cdwpdrv — Brother’s proprietary driver
printer-driver-brlaser — Open source alternative
brscan4 + brscan-skey — Scanner drivers (why not)

At least when the IP is fixed, the drivers will be ready.

The Lessons

mDNS can see devices that IP can’t reach. Layer 2 broadcast != Layer 3 routing.

Power surges can reset network configs. Devices might fall back to static IPs from years ago.

Check the subnet before debugging the driver. I spent an hour reinstalling drivers before I pinged the IP.

Physical access is sometimes required. No amount of SSH will fix a printer control panel.

The printer was right there. Broadcasting its presence. Telling everyone it existed. But nobody could reach it. Story of my homelab sometimes.