Diagnosis
The intermittent connectivity on the HP LaserJet Pro M404dn is typically caused by a "DHCP Lease Timeout" or a "Network Sleep" state. When the printer enters a deep sleep mode to save power, the wireless network interface card (NIC) often fails to maintain its handshake with the router. The router eventually sees the device as inactive and reassigns its IP address to another device on the network. When the printer wakes up, it attempts to communicate using an IP address it no longer owns, resulting in a "Printer Offline" status that is only resolved by a hard reboot, which forces a new DHCP request. Furthermore, this model often struggles with "Band Steering" on modern dual-band routers (WiFi 6 or Mesh systems). If the router attempts to push the printer from the 2.4GHz band to the 5GHz band, the M404dn's network chip may fail to authenticate the switch, causing the connection to drop entirely. You can confirm this by checking the printer's control panel during a dropout; if the wireless icon has a red 'X' or the IP address displays as 0.0.0.0, the printer has lost its lease or its handshake with the access point.
How to Fix It
To resolve this, you must move the printer from a Dynamic IP (DHCP) to a Static IP address. This ensures the router reserves a specific "parking spot" for the printer that never expires.
- On the printer's control panel, press the Menu button.
- Navigate to Network Settings and select TCP/IP Settings.
- Select IPv4 Config and change the setting from Automatic (DHCP) to Manual.
- Enter a Static IP address. To avoid conflicts, choose an address high in your range (e.g., if your router is 192.168.1.1, set the printer to 192.168.1.200).
- Enter the Subnet Mask (typically 255.255.255.0) and the Default Gateway (your router's IP address, e.g., 192.168.1.1).
- Press OK or Save to apply the changes.
- Restart the printer by powering it off for 10 seconds and powering it back on.
- On your computer, go to Control Panel > Devices and Printers, right-click the M404dn, select Printer Properties > Ports, and ensure the printer is mapped to the new Static IP address you just assigned.
If That Didn't Work
- Disable Energy Efficient Ethernet (EEE): Access the printer's Embedded Web Server (EWS) by typing the printer's IP address into a web browser. Go to the Networking tab, select Energy Efficient Ethernet, and set it to Disabled. This prevents the NIC from entering a low-power state that drops the connection.
- Separate your WiFi Bands: If you use a Mesh system or a single SSID for both 2.4GHz and 5GHz, create a separate "Guest" network or a dedicated 2.4GHz SSID specifically for the printer. The M404dn is significantly more stable on a dedicated 2.4GHz channel.
- Update the Firmware via USB: Sometimes the wireless drops are caused by a bug in the network stack. Download the latest firmware from the HP support site, but instead of updating over the air (which may fail if the connection drops), connect a laptop via USB and run the firmware update utility.
- Assign a DHCP Reservation: If you prefer not to use a manual IP on the printer, log into your router's admin panel, find the "DHCP Reservations" or "Static Lease" section, and bind the printer's MAC address (found on the back of the printer) to a specific IP address.
Heads Up
- Avoid IP Conflicts: When assigning a manual IP, always choose an address outside the router's automatic DHCP range (usually above .200) to prevent the router from assigning that same address to a new phone or laptop.
- Power Cycle Sequence: After changing network settings, always reboot the router first, then the printer, and finally the computer to clear the ARP cache.
- Avoid Signal Interference: Keep the printer at least 3 feet away from large metal objects or microwave ovens, as the M404dn's internal antenna is sensitive to electromagnetic interference.
- Security Protocols: Ensure your router is using WPA2-AES encryption. This printer can struggle with WPA3, which may cause it to disconnect randomly during re-authentication.