my computer and phone can't find the canon printer on the network anymore. it was working yesterday.

Diagnosis

The Canon PIXMA MG3620 has likely experienced a "DHCP Lease Expiry" or an IP address conflict. Because this model lacks a built-in LCD screen for network configuration, it relies on a handshake with your router. If your router rebooted or assigned the printer's previous IP address to another device (like a new tablet or smart bulb), the printer becomes "invisible" to your computer and phone despite appearing to be powered on. This often happens because the MG3620 is typically configured with a Dynamic IP. When the lease expires, the router may assign a new address that the Canon drivers on your PC cannot track. You can confirm this by looking at the Wi-Fi lamp on the printer panel; if it is flashing or completely off, the printer has lost its handshake with the wireless access point. If the light is solid but devices can't find it, the printer is on the network, but the communication port (UDP/TCP) is blocked or the IP has shifted.

How to Fix It

To restore the connection, you must force the printer to request a new handshake and then refresh the driver's target address.

1. Power cycle the hardware: Turn off the printer, unplug the power cable from the wall, and restart your wireless router. Wait 60 seconds before plugging the printer back in.
2. Initiate Wireless Setup: Press and hold the Wi-Fi button on the printer panel until the Power lamp flashes. Release the button. The Wi-Fi lamp should now be flashing quickly, indicating it is in "Cableless Setup" mode.
3. On your Windows PC or Mac, open the Canon IJ Network Device Setup Utility (this is installed alongside the MG3620 driver package). If you don't see it, search for "Canon" in your Start menu.
4. Select "Search for Printers" and choose the MG3600 series from the list. The utility will push the current SSID and WPA2 password from your computer to the printer.
5. Once the Wi-Fi lamp on the printer stops flashing and remains solid green, the connection is restored.
6. On your mobile device (iOS or Android), open the Canon PRINT Inkjet/SELPHY app. Tap the "Add Printer" icon and allow the app to scan the local network to re-link the device.

If That Didn't Work

• Perform a Network Reset: If the printer is stuck in a loop, press and hold the Stop/Reset button until the Power lamp flashes 21 times. This clears the internal network cache and removes any "ghost" IP assignments that might be blocking a new connection.
• Check Frequency Band: The MG3620 only supports 2.4GHz Wi-Fi. If you recently upgraded to a Dual-Band router (5GHz/2.4GHz), ensure "Smart Connect" or "Band Steering" is disabled in your router settings, or create a separate 2.4GHz SSID. The printer cannot "see" 5GHz networks.
• Disable Firewall Blocking: On Windows, go to Control Panel > System and Security > Windows Defender Firewall. Select "Allow an app or feature through Windows Defender Firewall" and ensure that "Canon IJ Network Tool" and "Canon Printer" have both Private and Public checkboxes checked.
• Assign a Static IP: Access your router's admin page (usually 192.168.1.1 or 192.168.0.1). Find the printer in the "Connected Devices" list and select "Reserve IP" or "Static IP." This prevents the printer from changing addresses in the future.

Heads Up

• Avoid placing the printer directly next to the router; keeping a distance of 3-5 feet prevents signal saturation (interference) that can cause the connection to drop.
• If you change your Wi-Fi password, you must repeat the "Cableless Setup" process entirely, as the MG3620 cannot update passwords automatically.
• Keep the printer's firmware updated via the Canon IJ Network Tool to resolve known bugs regarding sleep-mode disconnection.
• If the Wi-Fi lamp flashes orange, it indicates a "Communication Error"—this usually means the password entered during setup was incorrect.