Articles on: Troubleshooting

Why is my Duet-powered printer offline?

Why is my Duet-powered printer offline?


Duet boards (Duet 3, Duet 2 and other RepRapFirmware boards) connect to SimplyPrint through the SimplyPrint Client, a small app on a computer or Raspberry Pi on your network. It talks to the board over the network, the same way Duet Web Control does. When your printer shows offline, work through these steps in order.


What this guide covers


1. Check the Client is running and up to date

  1. Open http://localhost:8000 on the device that runs the Client, or http://<device-ip>:8000 from another computer.
  2. Go to Settings > About, click Check, and install any update.


Check: the Client opens, and Settings > About says it is up to date.


See How to update the SimplyPrint Client.


2. Check you can reach Duet Web Control

  1. From the computer that runs the Client, open the board's IP address in a browser.


Check: Duet Web Control opens. If it doesn't, the board is off, on another network, or has a new IP address - fix that first, because the Client can't reach it either.


3. Run Diagnose

  1. In the Client, click Printers and find the Duet printer.
  2. If it isn't online, click Diagnose on its card and follow the Try this next steps.


Check: Diagnose says the printer is reachable, and the printer comes online.


4. Check the address and password

  1. In the Client, click Edit on the printer's card.
  2. Address must be the board's current address, starting with http://, for example http://192.168.1.42.
  3. Password must match the Duet Web Control password, if you set one. If you didn't set one, leave it empty.
  4. Click Save changes.


Check: the printer reconnects and shows online in the Client.


Not sure whether the board has a password? Open Duet Web Control in a browser. If it asks for a password, the board has one. When you add a Duet, the Client checks this itself and only asks for a password if the board needs one, suggesting reprap, the RepRapFirmware default.


To stop the address from changing, give the board a fixed IP address or a DHCP reservation in your router.


Using the standalone Duet connector?

Before the SimplyPrint Client, Duet printers connected through a separate connector, the simplyprint-duet3d service. It still works, but Duet support now happens through the SimplyPrint Client: that is where we help with problems and where fixes land. If you are on the connector and have trouble, move to the Client first:


  1. On the device that runs the connector, run sudo systemctl disable --now simplyprint-duet3d.service, so only the Client connects the board to SimplyPrint.
  2. Install the SimplyPrint Client. See How to install the SimplyPrint Client.
  3. In the Client, click Add printer > Duet, and enter the board's IP address and password, if it has one.
  4. Click Set up in SimplyPrint on the printer's card and choose Link to existing, to keep the printer's history.


Check: the printer is online in SimplyPrint with its old name and history.


Still offline?

Download the Client's logs (Logs > download icon > Select all > Download) and send the .zip with your board type and RepRapFirmware version. See Manage the SimplyPrint Client: download the logs.


Updated on: 27/10/2026

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