nbn box lights ยท FTTC
FTTC box lights: what each one means
Fibre runs to a small unit in a pit at your kerb, and a short run of copper covers the last few metres to your wall socket. You have a small nbn connection device with four lights, and your own router plugs into it. Below is every indicator on the nbn connection device 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 a small unit in a pit at your kerb, and a short run of copper covers the last few metres to your wall socket. You have a small nbn connection device with four lights, and your own router plugs into it.
Three solid blue lights is the sign that the device is connected to the nbn network, and it can take up to 15 minutes to get there after a restart. The reset button is on the side of the device, and nbn's guide says to hold it for 1 to 2 seconds. Your FTTC device is also powered from your premises, which is why the kerbside unit stops working when your power does.
Every light on the nbn connection device, 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 | The device is off. | Plug it in and switch the power outlet on. |
| Blue | Power is running to the device. | Nothing to do. | |
| Connection | Off | The device is not connected to the nbn equipment outside your home. | Check every cable is seated properly. You should hear a click when the phone cable seats. |
| Blue, blinking | The device is starting up. | Wait for setup to finish, which can take up to 20 minutes, and the light should go solid blue. | |
| Solid blue | Connected to the nbn equipment outside your home. | Nothing to do. | |
| Solid red, or blinking red | There may be a line fault or a problem with the connection device. | nbn's instruction here is specific and unusual: turn the power to the connection device off, then contact your provider. Do not leave it powered while you wait. | |
| Alternating red and blue | There may be a line fault, such as a telephone left off the hook. | This one is often yours to fix. Unplug every phone, fax, alarm dialler and anything else from every telephone wall socket in the house, then look again. If the light clears, plug them back one at a time until it returns and you have found the culprit. | |
| DSL | Off | The broadband link is down. | If Power and Connection are solid blue but DSL is out, contact your provider. That combination points at the line rather than your gear. |
| Solid blue | The device is synchronised. | Nothing to do. | |
| Blue, blinking | Synchronising, or a software update is running. | Wait for it to go solid blue. | |
| LAN | Off | No Ethernet connection to the device. | Check the cable to your router and that your router is switched on. |
| Blue or amber, solid or blinking | Data is flowing between the connection device and your router. | Nothing to do. |
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 FTTC 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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