set up my 2855e but it won't connect to wifi, keeps saying connection failed. my phone and laptop are fine.

Diagnosis

The connection failure on the HP DeskJet 2855e is almost always caused by a frequency mismatch between the printer's wireless card and your modern router. This printer is designed to operate exclusively on the 2.4GHz band. Most modern routers use "Smart Connect" or "Band Steering," which merges the 2.4GHz and 5GHz frequencies into a single SSID (network name). When the HP Smart app attempts to hand off the network credentials, the printer often fails to "handshake" because the router is trying to force it onto the 5GHz band, which the 2855e hardware cannot physically see. Additionally, this specific model often gets stuck in a "half-configured" state where it thinks it is in setup mode but has already partially registered a failed IP address. This creates a loop where the HP Smart app reports a "Connection Failed" error because it cannot find the printer on the network, while the printer believes it is still waiting for a command. You can confirm this by looking at the Wireless light on the control panel; if it is blinking rapidly, it is in setup mode, but if it is solid or off, the printer is stuck in a ghost connection state.

How to Fix It

To resolve this, you must force the printer back into a clean setup mode and ensure your device is communicating on the correct frequency. Follow these exact steps:

1. Hard Reset the Network Settings: On the printer control panel, press and hold the Wireless button and the Cancel button (the X) simultaneously for exactly 5 seconds. Release both. The power light will flash, and the wireless light will begin to blink, indicating the printer is now in "Setup Mode."
2. Force 2.4GHz on your Mobile Device: If your router has separate names for 2.4GHz and 5GHz (e.g., "Home_WiFi" and "Home_WiFi_5G"), manually connect your phone to the 2.4GHz version before opening the app. If you have a single SSID, temporarily move your phone further away from the router (to the edge of the house) to force the phone to switch to the longer-range 2.4GHz band.
3. Clear the HP Smart Cache: Close the HP Smart app completely. On Android, go to Settings > Apps > HP Smart > Storage > Clear Cache. On iOS, swipe the app away to kill the process.
4. Restart the Setup: Open HP Smart. Tap the "Add Printer" or the plus (+) sign. The app will now search for printers in setup mode. Select the "DeskJet 2800 series" when it appears.
5. Enter Credentials Manually: When prompted for the WiFi password, type it in carefully. If the app asks to "Join a Network," ensure you select the 2.4GHz band.
6. Finalize HP+ Activation: Once the connection is established, the app will ask to activate HP+. Follow the prompts to link your account, as the 2855e requires a cloud connection to complete the initial firmware handshake.

If That Didn't Work

• Disable "WPA3" Security: Many new routers use WPA3 security by default. The DeskJet 2855e often struggles with this protocol. Log into your router's admin panel (usually 192.168.1.1 or 192.168.0.1) and change the security setting from "WPA3" or "WPA2/WPA3 Mixed" to "WPA2-AES (CCMP)."
• Use the Wi-Fi Direct Method: If the router continues to block the connection, enable Wi-Fi Direct on the printer. This creates a temporary peer-to-peer network between your laptop and the printer, bypassing the router entirely. Once connected via Wi-Fi Direct, you can often push the router settings to the printer through the HP Smart app.
• Disable VPNs and Firewalls: If you are using a laptop for setup, disable any active VPN (like NordVPN or ExpressVPN) and temporarily disable third-party firewalls (like Norton or McAfee). These often block the UDP ports required for the HP Smart app to discover the printer on the local subnet.
• Change the DHCP Lease: In your router settings, assign a "Static IP" or "DHCP Reservation" to the printer's MAC address. This prevents the printer from losing its connection every time the router refreshes its IP lease, which is a common cause of the "Offline" status on this model.

Heads Up

• Avoid USB Setup: Do not attempt to set up the wireless connection via a USB cable. This often confuses the driver installation and can lead to a "Printer Not Found" error even after the WiFi is connected.
• Firmware Updates: Immediately after connecting, check for firmware updates in the HP Smart app. HP frequently releases patches specifically to improve the 2.4GHz stability for the 2800 series.
• Power Cycle Order: If you change router settings, always reboot in this order: Router first, then wait 2 minutes, then turn the printer on.
• Ink Cartridge Warning: The 2855e will often refuse to complete the network setup if the setup cartridges are not properly seated or if the orange plastic tabs are still attached. Ensure cartridges are fully clicked in.