When your HP LaserJet Pro M404dn printer not found error appears during setup or suddenly disappears from your network, it prevents critical business documents from printing. This wired Ethernet and USB laser printer commonly drops off Windows, Mac, and network device lists due to IP address conflicts, driver corruption, firewall blocking, or physical connection problems. Our certified printer repair specialists have resolved thousands of "printer not found" cases—here's the complete troubleshooting guide to get your M404dn back online.
Network and Connection Troubleshooting
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Verify Physical Ethernet Connection: Check that the RJ-45 cable is firmly seated in the M404dn's rear Ethernet port and your router/switch. The amber and green activity LEDs near the port should blink during data transmission. Try a different Cat5e or Cat6 cable, and test another switch port. For USB connections, use the USB-B port on the printer's rear panel and avoid USB hubs—connect directly to your computer.
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Print a Network Configuration Page: On the M404dn's control panel, press the OK button, navigate to Network Setup > Network Config, then select Print Network Configuration Page. This page reveals the printer's current IP address, subnet mask, gateway, and connection status. If the IP shows 169.254.x.x, the printer failed to obtain an address from your DHCP server—indicating a network infrastructure issue requiring router troubleshooting.
Assign a Static IP Address: From the control panel, go to Network Setup > TCP/IP Config > Manual. Enter an IP address outside your router's DHCP range (typically 192.168.1.50-192.168.1.199). Set the subnet mask to 255.255.255.0 and gateway to your router's IP. This prevents IP conflicts that cause the HP LaserJet Pro M404dn printer not found error when the DHCP lease expires or another device claims the address.
Driver and Software Fixes
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Remove and Reinstall HP Smart or HP Easy Start: Uninstall existing HP software through Windows Settings > Apps or Mac Applications folder. Download the latest HP Smart app from 123.hp.com or the full driver package for the M404dn. During installation, select "Network" connection type and allow the installer to discover the printer by IP address if automatic detection fails. The HP Smart diagnostic tool can automatically detect and fix printer support issues including firewall conflicts.
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Clear the Print Spooler and Reset Printing System: On Windows, press Windows+R, type services.msc, stop the Print Spooler service, delete contents of C:\Windows\System32\spool\PRINTERS, then restart the service. On Mac, go to System Settings > Printers & Scanners, right-click the printer list area, and select "Reset printing system." These steps eliminate corrupted jobs that can make a functioning printer appear offline or undiscoverable during fix printer attempts.
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Configure Windows Firewall and Antivirus Exceptions: The M404dn communicates on ports 9100 (RAW), 515 (LPR), and 631 (IPP), plus Bonjour/mDNS on UDP port 5353. Open Windows Security > Firewall > Allow an app, ensure "HP Smart" and "Spoolsv" are checked for Private and Public networks. Third-party antivirus (Norton, McAfee, Bitdefender) often blocks printer discovery—temporarily disable network protection during setup, then add printer IP ranges to trusted zones for ongoing tech support reliability.
⚠️ Important: Never download M404dn drivers from unofficial websites—counterfeit firmware and driver packages can compromise network security and permanently damage your printer's formatter board. Always use HP's official support portal or the HP Smart application's verified repository.
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Update Firmware and Perform a Cold Reset: Access the printer's Embedded Web Server (EWS) by entering its IP address in a browser. Navigate to the General tab > Firmware Update to install the latest version (currently 20231208 or newer). If discovery issues persist, perform a cold reset: turn off the printer, hold the OK and Cancel buttons while powering on, release when "Permanent Storage Init" appears. This restores factory network settings without affecting page counts or supply status—critical troubleshooting when previous configurations conflict with your current network.
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Why does my HP LaserJet Pro M404dn keep disappearing from Windows?
Intermittent disappearance typically stems from DHCP lease expiration causing IP address changes. The Windows print queue caches the old IP, making the printer unreachable. Assign a static IP on the printer or create a DHCP reservation in your router using the M404dn's MAC address (found on the network config page). Also ensure WSD (Web Services for Devices) is disabled in printer settings, as this unreliable protocol often causes discovery failures in favor of stable TCP/IP port 9100.
Can I connect the M404dn wirelessly if Ethernet fails?
The HP LaserJet Pro M404dn does not include built-in Wi-Fi—it's Ethernet and USB only. For wireless printing, connect it via Ethernet to a wireless router, or add an HP JetDirect ew2500 802.11b/g wireless print server. Alternatively, share the printer through a connected Windows or Mac computer. The M404dn's sibling, the M404dw, includes native wireless if you need direct Wi-Fi capability without additional hardware.
How do I find the M404dn if it has a 169.254.x.x IP address?
A 169.254.x.x address indicates Automatic Private IP Addressing (APIPA) failure—the printer couldn't reach a DHCP server. Check that your Ethernet cable and switch/router are functional. Connect a laptop directly to the printer with a crossover cable, or reset the router. Once normal IP assignment resumes, the printer should appear. Persistent APIPA often requires router DHCP troubleshooting or replacing a failed network formatter in the printer, which may need professional printer repair service.