Troubleshooting the Optical Network Terminator (ONT)

Your Optical Network Terminator (ONT) has a number of status lights. Its Power, DSL and LAN1 lights should all glow a steady green. If any light is flashing or switched off, select the option which describes its status:


Power light is off (this is the right-hand status light)

The mains is unplugged or there is a problem with the power supply or your modem. To check:

  1. Check that the Modem's plug is in and switched on at the mains socket.
  2. Unplug from the mains and check that your modem’s power cable is correctly inserted into the power socket underneath the modem.
  3. Plug the modem’s power cable back into mains power. Switch on the modem.
  4. If the Power light is still off, you'll need to get in touch. Find our contact details by clicking the contact us link on this page.
  5. Please have your computer turned on if you call.

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PON and LOS lights both flashing (these are the two left-hand lights)

Your modem is connecting. Please wait for a while (up to five minutes). If the the PON light does not turn solid green:

  1. Check if anything, such as network maintenance, is affecting internet performance by viewing BT Service Status.
  2. Check that the thin white fibre optic cable is fully inserted
  3. If the PON and LOS lights are still both flashing , disconnect the power cable, wait a few moments, reconnect the power cable and wait a few more minutes for the Power light to switch on.
  4. If you still have problems, you'll need to get in touch. Find our contact details by clicking the contact us link on this page.

Please have your computer turned on if you call.

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Relevant Port light is off

These are numbered 1-4 and correspond to the Port socket underneath the modem into with the Ethernet cable to your Fibre Hub is connected. Usually this will be Port 1. If this is off (or all lights are off), the Optical Network Terminator (ONT) cannot detect your Fibre Hub. To establish a connection:

  1. Check that the red end of your broadband cable is correctly inserted into your Fibre Hub's red Broadband socket.
  2. Check that the other end of the broadband cable is correctly inserted into the one of the Port sockets on the Optical Network Terminator (ONT). This will usually be Port 1.
  3. If the modem's Port light is still off, disconnect the modem's power cable, wait a few moments, reconnect the power cable and wait a few more minutes for the Power light to switch on.
  4. If the Fibre Hub's Power, Broadband, and Internet lights do not glow a steady green, please see Troubleshooting the Fibre Hub.
  5. If the Port light is still off, you'll need to get in touch. Find our contact details by clicking the contact us link on this page.

Please have your computer turned on if you call.

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