The printer won't connect to Wi-Fi or the app can't find it

Symptom

The printer doesn't show as connected to the network, doesn't get an IP address, or the app or browser can't find it even though it worked before.

Likely causes, from most to least likely

1. The network is 5 GHz only and the printer's Wi-Fi module only works on 2.4 GHz (as with Prusa printers, for example).
2. Network name or password entered wrongly, or with extra spaces in a configuration file.
3. Weak signal or interference: the printer joins the router but doesn't get an IP address.
4. The phone or computer isn't on the same network as the printer.
5. The printer's IP address has changed: it's assigned automatically and can change over time.
6. On some systems, the network name has unsupported characters or the network uses roaming, which not all devices support.

Checks to tell which one it is

• Check the printer's network menu for its status and whether it has an IP (IPv4) address.
• Check on the router that the network broadcasts on 2.4 GHz.
• Confirm that the phone or computer is connected to the same network as the printer.
• Move the printer closer to the router (or vice versa) and see whether the connection status changes.

Before you start

Before taking anything apart, cleaning or adjusting it, switch the printer off and unplug it, unless a step says otherwise, and do not touch the nozzle, the heater block or the bed until they have cooled down. If in any doubt about electricity, heat or moving parts, stop and ask a professional.

Step-by-step fix

1. Use a 2.4 GHz network

   Connect the printer to a 2.4 GHz network. If your router only broadcasts on 5 GHz, enable the 2.4 GHz band in its settings.

   Check: The printer shows as connected.

   If that does not fix it: Enter the name and password again.

2. Enter the name and password again

   Run the printer's Wi-Fi wizard again and type the network name and password carefully. If you use a configuration file, leave no spaces around the equals sign.

   Check: The printer connects and shows an IP.

   If that does not fix it: Improve the signal.

3. Improve the signal

   Move the printer and router closer or remove obstacles between them. If the printer has joined but has no IP yet, wait a few minutes: a short drop can be normal while it connects.

   Check: The printer gets an IP and keeps it.

   If that does not fix it: Look up its current IP.

4. Look up the printer's current IP

   Read the IP address in the network menu and use it in the app or browser, with the phone or computer on the same network. As the IP can change, reserve a fixed one in the router or set it as static if your printer allows it.

   Check: The app or browser finds the printer.

   If that does not fix it: Try a cable.

5. Use a network cable if your printer has one

   If your printer has an Ethernet port, connect it to the router by cable and select it as the active interface in the network menu.

   Check: The printer gets an IP over the cable.

   If that does not fix it: Update the firmware.

6. Update the firmware

   Install the latest firmware for your model; some printers also update the Wi-Fi module from their network wizard.

   Check: The connection works reliably.

   If that does not fix it: Contact your manufacturer's support.

Prevention

• Reserve a fixed IP for the printer in the router.
• Keep the printer within range of a good 2.4 GHz signal.
• Avoid renaming the network or using odd symbols in its name.

Still not fixed?

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Printers it applies to

Any FDM (filament) 3D printer, from any brand.

Official sources

This guide summarises the official documentation linked here:

• PrusaLink Troubleshooting · Prusa Research
• Network Connection (CORE One L, CORE One, MK4S, MK3.9S) · Prusa Research