Why is my printer offline?

A printer shows offline in SimplyPrint when SimplyPrint stops hearing from it. What to check depends on how the printer is connected. Most printers today connect through the SimplyPrint Client, so this guide starts there, then covers OctoPrint, Klipper and Prusa.

Find how your printer connects

Not sure? The setup guide at simplyprint.io/setup-guide shows the method for your model.

Printers on the SimplyPrint Client

The Client runs on a computer, Raspberry Pi, Docker host or Home Assistant machine on your network and talks to the printers locally. Work through these steps in order.

1. Check the Client is running

1. Open http://localhost:8000 on the device that runs the Client, or http://<device-ip>:8000 from another computer.
2. If it doesn't open, start the Client or restart that device. On Windows and Mac, look for the SimplyPrint icon in the system tray or menu bar. On Linux or a Raspberry Pi, run systemctl status simplyprint-client.

Check: the Client opens and lists your printers.

The device must stay on and awake. A Windows PC or Mac that goes to sleep takes every printer offline.

2. Update the Client

1. In the Client, go to Settings > About and click Check.
2. Click Install update if one is offered. Running prints keep going while the Client restarts.

Check: Settings > About shows the new version.

Why first: most "it suddenly stopped working" cases, such as Bambu Lab printers failing to connect over MQTT or a printer that went offline after a firmware update, are already fixed in a newer version. On Docker, see How to update the SimplyPrint Client.

3. Run Diagnose

1. Click Printers in the Client and find the offline printer.
2. Click Diagnose on its card.
3. Read what it found and follow its Try this next steps.

Check: run Diagnose again after each fix, until it says the printer is reachable.

Diagnose tells you whether the printer answers at its IP address, and for Bambu Lab printers whether the access code and serial number are right.

4. Fix a changed IP address

If Diagnose says the printer service is not reachable, the printer has often got a new IP address from your router.

1. Find the printer's current IP address on its screen or in your router.
2. In the Client, click Edit on the printer's card, enter the new IP address and click Save changes.
3. In your router, give the printer a fixed IP address or a DHCP reservation, so it doesn't change again.

Check: the printer shows online in the Client.

5. Check the Wi-Fi

• Mesh or several access points: a printer can roam to an access point with a weak signal and keep dropping out. Lock it to one strong access point, or move the access point closer.
• Guest network or a separate VLAN: the Client and the printer must be able to reach each other. Put them on the same network.
• Test from the same computer: if the printer's own app or slicer, or a ping to its IP address, can't reach it from the Client's computer either, the problem is the network or the printer.

Check: the printer stays online for several minutes.

6. Several printers stalled at once? Restart the host

When many printers go offline or stall at the same time, the problem is usually the device that runs the Client, not the printers.

1. Restart the Client from the status menu in the bottom-left corner (Restart).
2. If that doesn't help, restart the computer or Raspberry Pi it runs on.
3. If printers still don't respond, restart the printers too.

Check: the printers come back online in the Client and in SimplyPrint.

After reinstalling the Client

A fresh install starts without printers, so your printers stay offline in SimplyPrint until you add them again. Add each printer in the Client, click Set up in SimplyPrint, and choose Link to existing. That keeps each printer's name and print history. See Manage the SimplyPrint Client.

Next time, a Client backup saves you the work. The Client makes one every day, under Settings > About > Configuration backup.

Brand-specific help

• Why is my Bambu Lab printer offline? - access code, LAN mode, prints stuck on "Download" and the file transfer ports (990 and around 50000-50100)
• Why is my Elegoo printer offline?
• Why is my Duet-powered printer offline?
• Why is my UltiMaker printer offline?

If a printer still shows Printing while it is offline, that is the last state SimplyPrint knew. It updates when the printer is back.

OctoPrint

SimplyPrint connects through the SimplyPrint plugin in OctoPrint.

1. Is the printer connected in OctoPrint itself? If not, fix that first.
2. Is the SimplyPrint plugin installed and enabled?
3. Is the USB cable a data cable, not a charge-only cable?
4. Does the Raspberry Pi have a good power supply? Undervoltage causes disconnects.

Full guide: Why is my OctoPrint-powered printer offline?

Klipper (Mainsail or Fluidd)

SimplyPrint connects through Moonraker, the same service Mainsail and Fluidd use.

1. Can you open Mainsail or Fluidd? If not, the printer's host has a problem.
2. Is [simplyprint] in your moonraker.conf?
3. Restart Moonraker from the web interface.

Full guide: Why is my Klipper-powered printer offline?

Prusa with SimplyPrint firmware

Check that the SimplyPrint firmware is installed and that the SimplyPrint tab shows in the printer's network settings.

Full guide: Why is my Direct Prusa integration printer offline?

Still offline?

For printers on the Client, download its logs (Logs > download icon > Select all > Download) and send the .zip with your printer model and Client version. See Manage the SimplyPrint Client: download the logs.

Related articles

• How to install the SimplyPrint Client
• How to update the SimplyPrint Client
• Manage the SimplyPrint Client: logs, password, backups and printers
• Connect your printers with the SimplyPrint Client
• Why does my printer show as "Not connected"?

Updated on: 27/10/2026