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Cylinder offline or not connecting

Find the fault by how the cylinder connects: TP-Link powerline, hard-wired or Nano router.

An offline cylinder keeps heating to its last schedule, so the customer still has hot water, but it loses app control and smart features, and support can't run remote checks. Start with the home broadband, then follow the checks for how the cylinder is connected.

Check the home internet first

Do other devices connect through the same router?

  • If not, it's a broadband or internet provider fault, not a Mixergy issue. Retest once the home connection is back.
  • If yes, follow the checks below for how the cylinder is connected.

TP-Link powerline (1.0 controller)

1. Check the adapter

Is the adapter plugged into the mains and connected to the home router? Are the Power and Ethernet LEDs on?

  • If there are no lights on the plug, replace the powerline adapter.
  • If yes, go to step 2.

2. Check the socket

Is the adapter in a plain wall socket with no USB ports, no extension lead and no surge protection in the path?

  • If not, move it to a plain wall socket. Surge protection at the consumer unit can cause dropouts even after years of stable connection, so flag it if it's fitted.
  • If yes, go to step 3.

3. Check the LEDs

After a few minutes, are all the LEDs lit (cylinder connected)?

4. Check the gauge and the app

Is the blue Wi-Fi light now showing on the gauge, and is the cylinder visible in the app?

  • If yes, it's reconnected. Ask support to confirm the cylinder is reporting on the servers.
  • If pairing won't hold, the house wiring may not carry a reliable powerline signal (for example separate ring mains or interference). Switch method: hard-wire to the router if practical, or fit a Nano router. Support can talk you through either.
  • If it keeps dropping out with no clear pattern, contact Mixergy support with the MX number. Server logs show every disconnect and often reveal the cause, such as surge protection, interference or internet provider drops.

Hard-wired Ethernet

For the full set-up, see Connect a Version 1 controller by Ethernet (video) or Connect a Version 2 controller by Ethernet (video).

1. Check the cable connections

Is the cable connected at both ends, to the router port and to the Ethernet port on the cylinder PCB (not the Zone bus)?

2. Check the router port and cable

Try a different router port, test the cable's integrity, and confirm the cable has all 8 cores populated and is Cat6 rated. A 2-pair cable can carry internet for other uses but causes unreliable behaviour.

3. Power cycle and recheck

Is the connection restored after checking the cable and ports and power cycling?

  • If yes, it's resolved. The cause was a faulty cable, a loose termination or a dead router port.
  • If the cable and router check out but the cylinder is still offline, suspect the PCB Ethernet interface. Contact Mixergy support, who'll check the server history, and photograph the PCB (in the white box) for any burnt components. A replacement controller and an engineer visit may be needed.

Nano router (TP-Link TL-WR802N)

Is the green light solid? Solid means it's connected to the home Wi-Fi. Flashing means it isn't set up or has lost the network.

  • If it's flashing or off, reconfigure the Nano to the home Wi-Fi, then plug its Ethernet feed into the cylinder. See Set up the Wi-Fi kit for a Version 1 controller (video). A changed Wi-Fi password or a new router is the usual cause.
  • If it's solid but the cylinder is still offline, the fault is on the Ethernet or PCB side. Follow the hard-wired Ethernet checks above.