This article will guide you through the troubleshooting for speed issues on an NBN™ Fibre to the Building or Fibre to the Node (FTTB/FTTN) service.

Please note that if you complete this troubleshooting and suspect you may have a speed fault, there is a set of advanced troubleshooting that is required in order to lodge a speed fault.

Why doesn’t my speed match the maximum speed of my NBN™ plan?

The NBN™ plan speeds are theoretical maximum speeds, not guaranteed. There are several factors that can affect your NBN™ speed, which are explained in more detail here. But they can include:

  • The speed capabilities of your computer and/or devices
  • The speed capabilities of your wireless router (if used)
  • Data or Network congestion


  • When running a speed test on an Ethernet cable-connected computer, your results are significantly slower than usual
  • These slow speeds occur on all connected computers/devices, not just one
  • Files take a long time to download despite being small in size

Things to check first

Potential cause
Try this:
Weak WiFi signalTo rule out a weak WiFi signal, you should test your speed on a computer connected to your modem with an Ethernet cable.
Damaged or loose cablesCheck that all cables are in good condition and plugged in securely.
Virus or malware infectionRun an antivirus/anti-malware scan using your antivirus software. If you need a hand with this, please contact your security software’s Customer Support.
Firewalls or other antivirus software settingsTest your speed while firewalls/antivirus software is temporarily disabled. Please contact your security software’s Customer Support if you need a hand with this.
Data congestionTo rule out data congestion, reduce the number of connected devices on your home network.
Network congestionTest your speed at different times of the day, especially if your slow speeds only seem to occur around 5-8PM, which is a typical time for network congestion to occur.


  1. Firstly, you should check the ‘sync speed’ in your modem settings. ‘Sync speed’ is the speed at which your modem is synchronising with the NBN™ network.

This article covers how to do this on Australia Broadband modems which support NBN™ FTTB/FTTN services. If you purchased a VDSL2-ready modem elsewhere, please refer to the user manual or manufacturer’s website for support information on how to check this.

On a TG-1 or TG-789 Broadband Gateway

On a computer that’s connected to your TG-1 or TG-789 Broadband Gateway, open your web browser and go to After logging in, click the Broadband panel and then click + Show advanced options in the upper right-hand corner. Scroll down to Line rate – the speed listed next to the downwards arrow is your sync speed for downloads.

On a Budii Lite

On a computer that’s connected to your Budii Lite, open your web browser and go to After logging in, click 7. Status / Diagnostics in the top menu bar and then click D. ADSL Monitoring in the left-hand column. See Actual data rate in the table – the speed listed for ‘downstream’ is your sync speed for downloads.

2. If your sync rate is poor, please please call us on 1300 023 354 for further assistance.

If your modem has a good sync speed but your speed test results on connected computers are significantly slower, continue to the next step to troubleshoot potential interference on your home network.

3. Unplug all devices from every telephony/networking wall socket at your address, including modems, phones, pay TV boxes and EFTPOS terminals.

4. Plug your modem directly into the wall socket used for NBN™ FTTB/FTTN broadband (no line filter/splitter should be used for modem connections). This is known as “isolating” your modem, because it is now the only thing plugged in.

5. Connect one computer to your modem with an Ethernet cable. If you have any other computers cable-connected to your modem, unplug their Ethernet cables.


There are different kinds of Ethernet cables. We recommend using a Cat 6 or Cat 5e cable. While a Cat 5 cable will work, it may not support the speeds of your NBN™ service.

6. Turn off or disconnect any computers or devices connected to your WiFi network. Alternatively, some modem/routers may have a WiFi on/off switch you can use to temporarily disable your WiFi network.

7. Run a speed test. If your speeds are faster now, follow the advice below.

8. If your speeds are still slow, if possible, try using different phone cable to plug your modem into the phone socket, and a different Ethernet cable to plug your computer into your modem.

9. Run another speed test. If your speeds are faster now, follow the advice below.

10. If possible, plug in a different VDSL2-ready modem at your property and run another speed test. If another modem doesn’t give you poor speeds, the original modem may be faulty.

If a different VDSL2-ready modem also gives you slow speeds, then it’s safe to say that the original modem isn’t faulty.

11. If you continue to experience slow speeds, please call us on 1300 023 354 for further assistance. Please note that there is a set of advanced troubleshooting that is required in order to lodge a speed fault.

If speeds improve while your modem is isolated

  1. If your speed improves while your modem is plugged straight into the wall socket, that means that one of the other pieces of equipment you had plugged in (e.g. filter, cable, phone) was interfering with your home network.
  2. Ideally, you should plug in one device at a time and test your speed again before plugging in another device. This will help you identify any specific hardware that may be causing speed issues.
  3. If your speed drops again, the device you’ve plugged in is probably faulty or affecting your connection; or its cable may be damaged.
  4. We recommend replacing a cable or device if it is faulty. Remember that line filters should not be used when plugging in your modem.
  5. If you have more than one wall socket in your home, it’s also possible that internal wiring issues are causing connection interference. If you suspect this is the case (i.e. speeds drop once devices are plugged into a different wall socket, and changing devices does not resolve the issue) please contact an electrician who is registered with an ACMA-accredited registrar. This means that they are properly licensed to work on communications cables.