nbn® HFC Connection Box Status Lights

Checking the status lights on your nbn Connection Box (NCB) for nbn HFC can be useful for troubleshooting.

Select one of the links below to jump to a query:

Arris CM3500 nbn HFC Connection Box Status lights

This model was supplied from 19 March 2025 onwards.

Light	States and meaning
Off	Off = Nothing is plugged into the 2.5G port. Green = A device is plugged in with a CAT5e or CAT6 Ethernet cable. Yellow = A device is plugged in with an older CAT5 Ethernet cable, which may not support the full speed of your nbn HFC plan. We recommend switching to a CAT5e ot CAT6 Ethernet cable.

Light	States and meaning
Power	Off = No power. Green = Your NCB has power.
Downstream	Off = Your NCB is still searching for a connection, or has no power. Green = Your NCB can download data. Flashing green = A firmware upgrade is in progress - this should take 10 minutes or less.
Upstream	Off = Your NCB is still searching for a connection, or has no power. Green = Your NCB can upload data. Flashing green = A firmware upgrade is in progress - this should take 10 minutes or less.
Online	Off = No connection to the network. Green = Your nbn connection is working as expected.

This model was supplied before 19 March 2025.

Light	States and meaning
Power	Off = No power. Green = Your NCB has power.
Downstream	Off = No power. Green = Successful downstream connection. Flashing green = Your NCB is searching for a downstream connection. If the ONLINE light is on, a firmware upgrade is in progress.
Upstream	Off = No power or no downstream connection. Green = Successful upstream connection. Flashing green = Your NCB has a downstream connection and now it's searching for an upstream connection. If the ONLINE light is on, a firmware upgrade is in progress.
Online	Off = No connection to the network. Green = Successful network connection. Flashing green = Your NCB has found a downstream and upstream connection and now it's getting settings from nbn®.