nbn box lights ยท HFC
HFC box lights: what each one means
Fibre runs to your neighbourhood and the last stretch is the coaxial cable that used to carry cable TV. You have an nbn connection box with four lights on the front, and your own router plugs into it. Below is every indicator on the nbn connection box with nbn's own documented meaning, and the action that goes with it.
Last reviewed: 15 August 2026 · by Alien IT Solutions
What you are looking at
Fibre runs to your neighbourhood and the last stretch is the coaxial cable that used to carry cable TV. You have an nbn connection box with four lights on the front, and your own router plugs into it.
All four lights solid green is the working state, and nbn allows up to 30 minutes for them to get there after a fresh install or a power cut. The four lights read Power, Downstream, Upstream and Online from top to bottom. The white cable into the box is locked on deliberately, and nbn asks you to leave it alone to avoid damaging the box.
Every light on the nbn connection box, and what it means
This table is nbn's own documentation for this equipment, not one provider's summary of it. Where your provider's guide says something different about your specific hardware, follow theirs, because they know which model they sent you.
| Light | What you see | What it means | What to do |
|---|---|---|---|
| Power | Off | There is no power to the connection box. | Check the power supply is plugged in, switched on, and connected. If there is still no light, contact your provider. |
| Green, flashing | There is an issue with your connection box. | This is a fault, not a startup state. Contact your provider. | |
| Green, solid | Power is normal. | Nothing to do. | |
| Downstream | Green, solid | You can receive incoming data. | Nothing to do. |
| Green, flashing | A firmware update is running. | Allow up to 10 minutes. Services that ride on the connection, including some medical alarms, can stop working during an update, so keep a charged mobile handy. | |
| Upstream | Green, solid | You can send outgoing data. | Nothing to do. |
| Green, flashing | A firmware update is running. | Allow up to 10 minutes, as above. | |
| Online | Green, solid | The box is online. | Nothing to do. |
| Off or not solid | The box is not online. | If Power, Downstream and Upstream are solid but Online is not, the box has the cable but not the service. Contact your provider and quote exactly that. |
Now turn the light into a diagnosis
A light tells you the state. It does not tell you the cause, and the cause is what gets it fixed. Pick the pattern that matches what your connection has actually been doing, and you will land on the HFC answer for it.
- The internet drops out at the same time every dayIs it predictable, for example most evenings, or always around the same hour?
- The internet drops out when it rainsDoes it get worse in rain, or in the day or two after rain?
- The internet drops out then comes back on its ownDoes it come back without you touching anything, after seconds or minutes?
- The internet drops out every few minutesIs it constant, several times an hour, all day?
- The internet has been dead since a particular dayDid it stop on a particular day and never come back?
- The internet is slow but never actually drops outDoes it stay connected but run far below what you pay for?
Before you touch anything
- Do not go up a ladder or onto a roof. That includes fixed wireless antennas and dishes. nbn's own fixed wireless guide tells you to contact your provider rather than touch an outdoor unit mounted more than 2 metres off the ground. There is nothing you can fix up there that is worth a fall.
- Do not open the nbn connection box, and do not touch the pit or the lead-in cable. That equipment belongs to nbn, not to you or your provider. Fibre terminations carry laser light that you cannot see and should not look into. Opening it can also end your service and leave you liable for the repair.
- Leave the backup battery alone beyond what your provider's own script tells you. If you have the optional Power Supply with Battery Backup, follow your provider's instructions for it and nothing more.
- Burning smell, scorch marks, or a modem too hot to touch: stop. Switch it off at the wall, unplug it, and do not plug it back in. Tell your provider it needs replacing. There is no troubleshooting step that comes before this.
Where this comes from
Every light state and every figure on this page comes from the sources below, each checked on 15 August 2026. Where a provider's guide disagrees with nbn's, the provider is describing their own hardware and you should follow theirs.
While you are on the phone to them anyway
Most people only look hard at their telco account when something has gone wrong. Since you are already dealing with them, send the bill over. The audit is free, and we will tell you plainly where you are overpaying and what is worth challenging.
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