ONT Diagnostic Checks

MS3 Networks ONT

Identifying your ONT

The ONT (Optical Network Terminal), look for a small white box, mounted to a wall within your property (usually on the ground floor).

White MS3 ONT

A white MS3 ONT in working order should have a green "Power" and "PON" lights, the "Alarm" light should be off, and the "Data" light, however, could be a different color depending on the service you have, which can be either one of the following:

  • Green (1Gbps uplink)
  • Yellow (2.5Gbps uplink)
  • White (5Gbps uplink)
  • Blue (10Gbps uplink)

A white Nokia Cityfibre ONT with 3 lights on indicating this is in working order

 

Is your ONT power light off?

A White Cityfibre Nokia ONT with all the light indicators Off

 

Check that the power cable is securely connected to both the ONT and a working mains power socket. Make sure that the socket is switched on.

If you still don't have power, try plugging the ONT into a different mains power socket to make sure that the issue isn't with the socket itself.

If you've tried multiple power sockets and are still having trouble, it's possible that your ONT or power cable is faulty. In this case, please contact our Technical Support team for further assistance.

Is your ONT Alarm or Power light red, or PON off?

A White Nokia 2.5G ONT with a Red Power and Alarm light

 

Restart your ONT, disconnect the power cable for at least a minute before reconnecting it. Wait for around 2 minutes for the ONT to come back online to see if the lights no longer indicate an issue.

It may be you're affected by a wider issue in your area, you can check for outages on our Service Alerts page.

If you're in the clear, we'll try resetting your ONT.

If the lights still show the same issue. Get a pin, unfolded paper clip or a SIM card removal tool, then continuously press into the reset hole on the underside of your ONT for 10 -15 seconds.

All lights on your ONT go off or flash. Then release the button and wait around 2 minutes for your ONT to reset.

Is your ONT Data light off?

 

A White CityFibre Nokia ONT with the Data Light indicator Off

 

Make sure the Ethernet cable connecting your ONT to your router is secure and in place. This will be going into a Yellow socket and may be labelled "ETHERNET" on the underside of your ONT.

If you would like to check that the other side of the cable is going into the right port on your router you can find a guide here if you have a FRITZ!Box and here if you're using an eero.

If the cable is secure at both ends. Test an alternative Ethernet cable using the same steps above.

Is your ONT power light flashing Green or solid Amber?

A White Nokia CityFibre ONT with an Amber Power light indicator

 

When the power light flashing green, this indicates that the device has just powered on or is performing a "Firmware" download; when the light goes Amber, then the device is installing the software.

It is recommended that you leave this device for a short period of time while it carries out this update, this should take no longer than 15-20 minutes.

Still experiencing issues?

Does your ONT show all of the correct lights but you still don't have a connection?

It may be that you need some alterations to your Router Settings. You can find a handy guide to walk you through what to check/change here.

Contacting Technical Support

If the above steps do not resolve your connectivity issues, please contact our Technical Support team for further assistance.

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Phone | Zen Internet
Zen Internet - Home SalesSales
01706 902573
Phone | Zen Internet
Zen Internet - Customer EnquiriesCustomer Enquiries
01706 902001