Telstra Smart Modem: which one you have, what the light means, and how to fix it

If we sent you this link, turn the modem over first. The model number on the bottom or the back tells you which Telstra Smart Modem you have, and each one’s light means something slightly different, so find yours below and match the colour. Most of the time a loose cable or a restart sorts it. When the light says the connection itself is down and a restart doesn’t bring it back, an internet technician who tests from the NBN box through the house finds which part is broken.

Which Telstra Smart Modem do I have?

Look for the model number on the bottom or the back of the modem, then match it in the table below.

Telstra's modems by model number, as Telstra lists them (checked 20 October 2026)

Model number on the label	Which modem it is	What it looks like
Mongoose	Telstra Smart Modem Gen 4 (the Smart Modem 4)	Black matte, rectangular, one status light on the front
CobraXh	Telstra Smart Modem Gen 3 (the Smart Modem 3)	Slim and upright, black, a status light on the front panel
LH 1000 or DJA 0231	Telstra Smart Modem Gen 2	Upright, in a sturdy white housing
Mongoose-5GFW	Telstra Smart Modem Gen 4 5G	Black matte, rectangular. For Telstra's 5G Home Internet
Meteor 2 or AW1000	Telstra 5G Modem Gen 2, or the Telstra 5G Modem	Meteor 2: a black square with a curved top edge. AW1000: white and compact, with a row of lights on the front
DJA0230 or DJN2130	The original Telstra Smart Modem, or the Telstra Frontier Gateway	The older ones, with the light on top

Or in My Telstra: Services, your internet service, View your devices, then Telstra Smart Modem. Telstra’s page on telling which Telstra modem you have (opens in a new tab) has a photo of each.

If Telstra sent you an eero, or you use your own modem, Telstra says its lights may be different, so check that modem’s user guide.

What do the lights on the Telstra Smart Modem 4 mean?

The Smart Modem 4 has one light on the front that changes colour. On the NBN, Telstra says solid green means connected, white means starting up or connecting, blue means it’s on mobile backup, red means no connection, and flashing blue and green means a firmware update. Pick the colour you’re seeing:

Telstra Smart Modem 4

Model no. Mongoose. On the nbn, Opticomm or Satellite

Black matte finish in a rectangular design, with one status light on the front. Holding the button on the back, about halfway down on the left side, for 3 seconds turns the modem lights off.

Which one is yours?

Solid green White, slow White, fast Solid blue Blue and green Solid red

HealthyConnected.

• Front light Green Connected to nbn or Opticomm network or Satellite.

What to do. Once you have connected your Telstra Smart Modem 4 to the internet and powered up your modem, the front light will be a solid green. If nothing loads, plug a laptop into the modem with a cable. If the cable works, it is the WiFi; if not, contact Telstra.

Working on itPowered on and booting up.

• Front light White, flashing every 2 seconds Powered on, booting up.

What to do. Wait a few minutes for the modem to reconnect.

Working on itConnecting.

• Front light White, flashing every second Connecting.

What to do. Wait a few minutes. When it is connected the light turns solid green. If it turns red, follow the red light steps.

Working on itYour modem has switched to mobile backup (available on eligible plans).

• Front light Blue Mobile backup connection (Data+Voice calls, only on eligible plans).

What to do. Check for outages. If there are none, check the cables are connected securely, unplug the modem from the power wall outlet, plug it back in and wait a few minutes. On backup for more than a few hours and not a known issue: troubleshoot in My Telstra. Still blue: contact Telstra.

Working on itUpdating firmware.

• Front light Flashing blue and green Updating firmware. This could take up to 10 minutes, especially when connecting the modem the first time.

What to do. This could take up to 10 minutes, especially when connecting the modem the first time. If it takes longer than 10 minutes, restart the modem by unplugging and re-plugging it from the power wall outlet.

FaultNo connection.

• Front light Red No connection.

What to do. Check the cables are connected securely, unplug the modem from the power wall outlet, plug it back in and wait a few minutes. Check the status lights on your nbn connection box too. If you still have no connection, contact Telstra.

Light states read from Telstra, What do the lights on my Telstra modem mean?, 20 October 2026.

The Smart Modem 4's front light on the NBN, Opticomm or Satellite, in Telstra's words

The front light	What Telstra says it means
Solid green	Connected to nbn or Opticomm network or Satellite
White, flashing every 2 seconds	Powered on, booting up
White, flashing every second	Connecting
Solid blue	Mobile backup connection (Data+Voice calls, only on eligible plans)
Solid red	No connection
Flashing blue and green	Updating firmware. This could take up to 10 minutes, especially when connecting the modem the first time

Leave a firmware update alone. Only if it runs past 10 minutes does Telstra say to restart the modem at the power wall outlet.

What do the lights on the back mean?

The lights on the back of the Smart Modem 4 show the mobile signal for mobile backup. Telstra lists green 3 bars as a good signal, green 2 bars as ok, green 1 bar as poor, and no bars as no network. Telstra’s device guide names three more lights on the modem (WAN/DSL, Phone and Wi-Fi): WAN/DSL on means the modem is connected to the network, Phone on means a device is plugged into the Phone port, and a steady Wi-Fi light means the WiFi is on.

No light at all? Telstra says holding the button on the back, about halfway down the left side, for 3 seconds turns the modem lights off, and its device guide says the same button turns them back on, so try that first.

On 5G or 4G Home Wireless, the colours change

If your Smart Modem 4 is on Telstra’s 4G Home Wireless instead of the NBN, Telstra says solid blue means connected to the mobile network. On the Smart Modem Gen 4 5G (Mongoose-5GFW), used for 5G Home Internet, solid green means connected. White and red mean the same as above. For red on either, Telstra adds: try moving the modem somewhere elevated and open, and check whether a mobile signal bar shows on the back.

What do the lights on the Telstra Smart Modem Gen 3 mean?

The Gen 3 also has one light on the front. Telstra says green means connected to the fixed network, blue means connected to 4G backup or the 4G mobile network, red means no connection, orange means it’s trying to connect, white means booting up, and no light means it’s offline.

Telstra Smart Modem Gen 3

Model no. CobraXh. Telstra also calls it the Smart Modem 3

A slim upright device in a black finish, with a status light on the front panel. A second light on the back shows the 4G mobile signal: green great, orange good, red weak.

Which one is yours?

Green White Orange Blue Red No light

HealthyConnected to the fixed network.

• Front light Green Modem is connected to fixed network.

What to do. If nothing loads, plug a laptop into the modem with a cable. If the cable works, it is the WiFi; if not, contact Telstra.

Working on itBooting up.

• Front light White Modem is booting up.

What to do. Wait a few minutes for the modem to reconnect.

Working on itTrying to connect.

• Front light Orange Modem is trying to connect.

What to do. Give it a few minutes. If it goes red or stays orange, restart the modem and the nbn connection box so they can reconnect.

Working on itOn 4G backup.

• Front light Blue Modem is connected to 4G backup or the 4G mobile network.

What to do. Check for outages. If there are none, check the cables are connected securely and restart the modem. On backup for more than a few hours and not a known issue: troubleshoot in My Telstra.

FaultNo connection.

• Front light Red Modem has no connection.

What to do. Make sure your cables are securely connected, including the Ethernet cable in the red WAN port. Check the status lights on your nbn connection box, then restart the modem and the box. Still red: contact Telstra.

Nothing onOffline.

• Front light Off Modem is offline.

What to do. Make sure the modem has power and its cables are securely connected, then restart it. Still no light: contact Telstra.

Light states read from Telstra, What do the lights on my Telstra modem mean?, 20 October 2026.

The Smart Modem Gen 3's front light, in Telstra's words

The front light	What Telstra says it means
Green	Modem is connected to fixed network
Blue	Modem is connected to 4G backup or the 4G mobile network
Red	Modem has no connection
Orange	Modem is trying to connect
White	Modem is booting up
No light	Modem is offline

The light on the back of the Gen 3 shows the 4G mobile signal. Telstra says green means the signal strength is great, orange means good and red means weak. So red on the back is about the backup signal, not your NBN connection.

What do the lights on the Gen 2 and the original Smart Modem mean?

On the Gen 2, a green light on the front means the modem is connected to your normal home internet, and blue means it’s connected to the Telstra Mobile Network. The mobile signal light is on the back: Telstra says it should be solid green or orange, which means the modem has contacted the mobile network, and if it doesn’t light up or is red, to contact Telstra.

Telstra Smart Modem Gen 2

Model no. LH 1000 or DJA 0231

A minimalist upright look in a sturdy white housing, with a light on the front. The mobile signal light is on the back.

Which one is yours?

Green Blue Signal light red

HealthyConnected to your normal home internet.

• Front light Green Your modem is connected to your normal home internet.
• Mobile signal, on the back Green The modem has successfully contacted the mobile network.

What to do. If nothing loads, plug a laptop into the modem with a cable. If the cable works, it is the WiFi; if not, contact Telstra.

Working on itConnected to the Telstra Mobile Network, the 4G mobile backup.

• Front light Blue Your modem is connected to the Telstra Mobile Network.
• Mobile signal, on the back Green The modem has successfully contacted the mobile network.

What to do. Check for outages, check the cables are connected securely, and restart the modem. Still blue: contact Telstra.

FaultThe mobile signal light is red.

• Front light Green Your modem is connected to your normal home internet.
• Mobile signal, on the back Red Contact Telstra, or message Telstra through the My Telstra app.

What to do. If the mobile signal light does not light up or is red, contact Telstra or message Telstra through the My Telstra app.

Light states read from Telstra, How do I stay connected with your Telstra Smart Modem?, 20 October 2026.

The original Telstra Smart Modem (DJA0230) and the Frontier Gateway (DJN2130) have an “online” light on top. Telstra says green means the modem is connected to your normal home internet, and magenta means it’s connected to the 4G backup or the Telstra Mobile Network. The mobile signal light is on top too: green for a great 4G signal, orange for good, red for weak. Telstra’s mobile backup page says the Frontier Gateway doesn’t support mobile backup.

Telstra Smart Modem and Frontier Gateway

Model no. DJA0230 (Smart Modem) or DJN2130 (Frontier Gateway)

The "online" light and the mobile signal light are on top of the modem. Telstra says the Frontier Gateway does not support mobile backup.

Which one is yours?

Green Magenta

HealthyConnected to your normal home internet.

• Online, on top Green Modem is connected to fixed network.
• Mobile signal, on top Green 4G mobile signal strength is great.

What to do. If nothing loads, plug a laptop into the modem with a cable. If the cable works, it is the WiFi; if not, contact Telstra.

Working on itConnected to the Telstra Mobile Network.

• Online, on top Magenta Modem is connected to 4G backup or the 4G mobile network.
• Mobile signal, on top Green 4G mobile signal strength is great.

What to do. Check for outages, check the cables are connected securely, and restart the modem. Still magenta: contact Telstra.

Light states read from Telstra, What do the lights on my Telstra modem mean?, and How do I stay connected with your Telstra Smart Modem?, 20 October 2026.

What does a red light mean, and how do you fix it?

A red light on the front of a Smart Modem 4 or Gen 3 means no connection. Telstra says that if the front light is red and there’s no mobile signal light on the back, you have no connection at all. These are Telstra’s steps, from its lights and troubleshooting pages:

1. 1

   Check for an outage

   Look up Telstra's outage checker on your phone, using mobile data, since the home WiFi is down. If there's an outage at your address, the fix is Telstra's and you only need to wait.

2. 2

   Check the cables

   Telstra says to check the cables are connected securely. On the NBN, that's the cable in the red WAN port on the modem, and its other end in the NBN box.

3. 3

   Unplug the power and plug it back in

   Unplug the modem from the power wall outlet, plug it back in, and wait a few minutes. The modem should then restart the connection process.

4. 4

   Contact Telstra

   If you still have no connection, Telstra says to contact it. Use the My Telstra app or Telstra's website, never a number from a text.

Look at the NBN box as well: Telstra’s troubleshooting page says to check its status lights. Your NBN connection box and what its lights mean has the box for each kind of NBN, with a panel like the ones above.

If one of the cables looks bent, crushed or chewed, try a spare network cable in its place before you ring.

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Product	What it is for	Link
UGREEN Cat6 lead, 2 m	Laptop to modem, modem to switch	View on Amazon for the UGREEN Cat6 lead, 2 m (opens in a new tab)

Why is my Telstra modem light blue?

On the NBN, a blue light means your normal connection has dropped and the modem has switched to mobile backup over Telstra’s mobile network. Telstra says mobile backup comes on eligible plans, is switched on automatically, and needs mobile coverage. On the original Smart Modem it shows magenta instead of blue.

What it means for you, from Telstra’s mobile backup page:

• The internet keeps going, but slower. Telstra says backup speeds on Home Internet plans are capped at 25/5 Mbps, and actual speeds may be lower.
• The home phone should still work on a Telstra plan with voice on the NBN, Opticomm or Satellite.
• It isn’t meant to replace the NBN. Telstra says its Customer Terms only permit mobile backup when your internet connection is unavailable, and only at your home address.
• It may not work in a blackout. Telstra says the Smart Modem may not work during a power outage. What keeps working in a blackout on the NBN covers the phone and any alarm on the line.

To get back to normal, Telstra’s steps match the red light’s: check for outages and the cables, then unplug the modem at the wall and plug it back in. If you’ve been on mobile backup for more than a few hours and it isn’t a known issue, troubleshoot in My Telstra:

1. 1

   Go to Services.

2. 2

   Select your internet service.

3. 3

   Scroll down to Your connection and select Improve your connection.

4. 4

   Select Test and troubleshoot internet and follow the prompts.

If the light is still blue after that, contact Telstra. Telstra’s own mobile backup page (opens in a new tab) lists the plans it applies to.

How do you restart a Telstra Smart Modem?

Telstra’s steps are to remove the power cable from the modem for 10 seconds, plug it back in, and wait a few minutes. Back online, the front light is solid green, or solid blue on 4G Home Wireless.

If you’re restarting the NBN box as well, Telstra says to switch it (or its battery backup unit) off at the wall, disconnect the battery unit’s power cord if you have one, and wait at least two minutes before turning everything back on. Turn the NBN box on first and the modem after it. How to restart the modem and the NBN box in the right order has the order and the waits, step by step.

Don’t push anything into the small hole next to Reset. Telstra’s guide for the Smart Modem 4 says holding a paper clip in it for at least 10 seconds restores factory defaults. That puts it back to how it left the factory, so anything you changed, such as the WiFi name or password, goes back to what’s on the label.

How do you log into a Telstra Smart Modem?

Type mymodem or 192.168.0.1 into a web browser on a device joined to the modem. On the Smart Modem 4 and Gen 3, Telstra says the password is the WiFi password printed on the bottom of the modem. Logging into your modem and changing the WiFi name and password walks through it, and points to Telstra’s page for the older models.

Which cable goes where on a Smart Modem 4?

On fibre to the premises, Telstra says the red end of the cable goes into the red WAN port on the modem, and the yellow end into the yellow UNI-D1 port on the NBN box, unless you’ve been told otherwise. On fibre to the curb, HFC and Fixed Wireless, it runs from the WAN port to the yellow port on the NBN box, which Telstra calls UNI-D or UNI-D1.

On fibre to the node and fibre to the building there’s no NBN box. Telstra says the grey cable goes from the grey DSL port into the phone socket closest to the front of the house, and that the modem must always be switched on for the home phone to make and receive calls. Telstra also says to put the modem up high in an open area, away from metal security screens, fridges, microwaves and TVs. If the WiFi still doesn’t reach the far rooms, a WiFi technician who gets the signal to the rooms that drop out is the visit for that.

Is it the modem or the NBN line?

If the light is red or blue and won’t come back to green after a restart, the trouble is usually the connection, not the modem. Then the NBN box lights, or on fibre to the node the phone socket and the wiring behind it, tell you more than the modem can.

If the modem’s light is solid green and nothing loads, the modem says it’s connected, but a light doesn’t prove traffic is getting through. Plug a laptop into the modem with a cable: if the cable works and the WiFi doesn’t, it’s the WiFi; if the cable doesn’t work either, it’s a call to Telstra. Why the modem lights are on but there’s no internet sorts that out light by light.

When to call us, and when to call Telstra

The checks above are yours to do, and an outage, a mobile backup that won’t switch back, or a modem that’s faulty are Telstra’s. If the Smart Modem itself has failed, contact Telstra, which looks after the modem under its own terms. We can’t replace a Telstra modem for you.

Call us when Telstra says the fault is in your home, or the light keeps going red and nobody can say why. We test from the NBN box through the house (the box, the cable to the modem, and the phone sockets and wiring on fibre to the node), tell you which part is broken, fix it when it’s on your side, and write it up for Telstra when it isn’t. If you’d rather someone sat with you to set up the modem, the WiFi and every device on it, that’s home tech support for the modem and everything joined to it. When Telstra and NBN each blame the other, an independent NBN technician who tests the line is the visit.

Not sure which you need? Send us a message with a photo of the modem’s light and the NBN box, or ring us on 02 9188 1577.