LOS light red on ONT FTTP

Hi folks,

Could someone who is familiar with FTTP and the Openreach ONT please confirm that if the LOS light on the ONT is red then there is a fault somewhere in the network, or the optical cabling, or the actual ONT itself, and that this red light doesn't indicate a fault in my ethernet cable that leaves the ONT to the WAN point on the router?

Also if FTTP cable, is just a continuation of the same optical fibre cable that brings it to the cabinet, and only the copper bit to the premises is replaced, or FTTP is a totally separate cable between the exchange in the homes totally bypassing the FTTC cabinets?

I do have a backup FTTC with the same ISP for the time being, so just reconnected up the telephone line to the same router that services the ONT (disconnected the WAN ethernet cable that goes into router from the ONT of course) and it is working fine, just prefer the FTTP connection for the greater download speed, but that LOS light is still red on the ONT box.

Many thanks for any help.

I can only handle this bit:-

In reply to a post by joemardo1:

Also if FTTP cable, is just a continuation of the same optical fibre cable that brings it to the cabinet, and only the copper bit to the premises is replaced, or FTTP is a totally separate cable between the exchange in the homes totally bypassing the FTTC cabinets?

Your almost right with your "totally separate cable …" at the end .

The fibre cable from whichever exchange it comes from, (frequently not your phone exchange), goes to an "aggregation node". For your FTTC there is a fibre cable from that node to an FTTC cabinet which near your phone cabinet, and those two cabinets are linked by a muli-pair copper cable. See this rather dated page. Many other FTTC cabinets are also served by that node.

FTTP towards you probably comes from the same exchange and node, but that's irrelevant. It comes from an aggregation point, with splitters at various points to provide fibres to distribution points. I think of distribution points being the same concept as the boxes for phone cables at the top of telegraph poles.

At the distribution points a fibre cable to your home is connected to one of the incoming cables, and goes direct to your ONT.

In reply to a post by joemardo1:

Could someone who is familiar with FTTP and the Openreach ONT please confirm that if the LOS light on the ONT is red then there is a fault somewhere in the network, or the optical cabling, or the actual ONT itself, and that this red light doesn't indicate a fault in my ethernet cable that leaves the ONT to the WAN point on the router?

Does this help?
https://www.bt.com/help/landline/fibre-home-phone-se...

LOS typically means "Loss Of Service"

The advice on that page is:
Check that the thin white fibre optic cable coming into your Openreach fibre modem is inserted and not damaged. Turn the Openreach fibre modem's power off, then back on and wait five minutes for the Openreach fibre modem to attempt to reconnect.

LOS fault indicates the Openreach ONT is not seeing any light down the fibre, or level has dropped to a level where it cannot work.

Time to report a fault if you have not already.

The FTTP fibre is a different fibre to the one feeding the FTTC cable so one can be up and the other can be down, or in the case of for example a JCB digging up lots of cable in the right spot both might be down.

A red LOS light means your ONT is not seeing enough light and needs to be reported to your service provider for service to be restored.

Yes, there’s a fault somewhere.

Report it via your ISP.

(Wild stab in the dark here ... you don’t live near Tilford in Surrey do you ?)

Thanks for all the replies, I'm actually in N Ireland, Openreach have only cabled the area 3-4 months ago.

I would hope that in a while most of any teething problems would be sorted as probably overall a reliable connection is more important than getting lightening speed.

Tried a few things switching off the power but no good.
Will have to call the provider on monday.
Thanks again.

Within weeks of fibre going live around here the repair teams where out fixing it.

How did and how long did this take to get fixed.?
I had BT FTTP installed today (N.I.) and there was a red LOS light immediately. The engineers explained there must be an issue in our newly laid village and will require investigation. Not a great start.