topic Re: Red light in Broadband

Red light

Suzy15 — Sat, 21 Jun 2025 14:16:36 GMT

I have a red fault light on the OCN?

Re: Red light

JimM1 — Sat, 21 Jun 2025 14:53:39 GMT

@Suzy15 Which one is RED they do have names under each on the OR ONT!

Link below may help you also.

What do the lights on the Openreach modem mean? | BT Help

Re: Red light

cookiemonsteruk — Sat, 21 Jun 2025 14:34:15 GMT

@Suzy15

@JimM1 the nature of the red fault is dependent on the ont

To find the true fault the customer would need to open the housing.

On older ont models the "fault" may be down to a back up battery loosing its charge

@Suzy15 could you post a photo of the ont

Re: Red light

JimM1 — Sat, 21 Jun 2025 14:58:33 GMT

@Suzy15 Some what better description from OR.

Openreach modem lights

Power

No light - If there is no light, the Openreach fibre modem is off.
Check the mains plug is in.
Green - If the light is green the Openreach fibre modem is on.
Check the PON and LOS status below.

PON and LOS lights

PON solid green - The fibre optic link to BT exchange is working and recognises your Openreach fibre modem.
Check physical connection at both ends of the cable between the Openreach fibre modem and hub. Try a new cable if needed.
PON flashing and LOS off - Openreach fibre modem is communicating with BT exchange for verification.
Wait until light turns solid green.
PON off, or PON and LOS both flashing - Fibre optic link is not connected or there's a problem between your property and the BT exchange.
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 5 minutes for the Openreach fibre modem to attempt to reconnect.

Re: Red light

cookiemonsteruk — Sat, 21 Jun 2025 15:03:25 GMT

@Suzy15

@JimM1 customer may be referring to this

Hard to say at the minute

Re: Red light

Deb3000 — Sun, 22 Jun 2025 09:35:16 GMT

Of course, it could be CityFibre now.

It varies with the make and model but as a general case...

Openreach ONT Lights (current model is Adtran, but have also been Nokia and Huawei)
POWER light:
Steady green...normal, flashing is starting up (or f/ware update...some models)
PON light:
Steady green...normal,
Flashing green....most likely connected but not authenticating, (an account problem, serial number mismatch etc.) (NB Could also be a whole range of other problems).
Red light (steady or flashing)....no logical connection i.e. fibre is lit & there is a physical connection but it is not connecting to the ISP. (Can also be the power button on some makes/models)
LAN or PORT:
Steady green...connected to the router, flashing is passing data, (amber is 100Mb/s?)
Alarm or LOS light:
Off...normal (Flashing green...f/ware update...some models)
Red light (steady or flashing)...loss of physical connection i.e. unlit/broken fibre, equipment failure. Power cut at the other end etc.

Cityfibre ONT lights (current model is Calix)
POWER light:
Steady green is normal, flashing amber is f/ware update & red is boot fail
BROADBAND light (equivalent of the PON light):
Steady green is normal, flashing green is trying to connect, red indicates a logical fault
SERVICE light (equivalent of the LOS light):
Steady green if OK, off is a physical fault
ETHERNET light (equivalent of LAN or PORT light):
Steady green means a connection to the router, flashing is passing data