Gtelecom | Business ISP for Voice, Data and Internet Services
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Troubleshooting Speed Issues

This article will explain how to troubleshoot speed issues for an ADSL, ADSL2+ or Naked DSL internet connection.


  • Connection speed much slower than it used to be
  • Files take a long time to download despite being small in size
  • Some websites don't load properly or suffer lag

Things to check

Check that your slow speeds aren't caused by the following before proceeding with the troubleshooting:

Potential cause
Try this:
Call dropouts or line noise on your home phone Always troubleshoot phone issues before focusing on any internet issues. Slow speeds may just be a side-affect from a phone problem.
Weak wireless signal Test your speed on a computer connected to your modem with an Ethernet cable.
Virus or malware infection Run an antivirus/anti-malware scan using your antivirus software. Please contact your security software's Customer Support if you need a hand with this.
Firewalls or other antivirus software negatively affecting internet performance Test your speed while firewall/antivirus software is temporarily disabled. Please contact your security software's Customer Support if you need a hand with this.
Data congestion Disconnect any additional devices from your home network.
Network congestion Test your speed at multiple times of the day, particularly if speed only slows around 5-8PM.
Modem settings or connection stability affecting speeds You should try putting your modem settings into "safe mode" (G.DMT mode). Instructions for Gtelecom modems are here. If you have a third-party modem, please consult its user manual or contact the manufacturer for support.


If you have Naked DSL, skip to step 4, as you won't have a landline phone service to check for phone faults.

  1. Unplug all devices from every phone socket, including modems, telephones, fax machines, other modems, pay TV boxes and EFTPOS terminals.
  2. Plug a standard telephone handset (with no filter) into the phone socket. Listen for a dial tone and make sure you can make a call without hearing noise interference. If you do hear line noise, troubleshoot that issue first.
  3. If you have no phone issues, unplug the telephone handset and instead plug your modem directly into the phone socket (with no filter).
  4. Connect one computer to your modem with an Ethernet cable. If you have any additional computers cable-connected to your modem, unplug their Ethernet cables.
  5. Turn off or disconnect any computers or devices connected to your wireless network. Alternatively, some modem/routers may have a Wireless on/off switch you can turn off to temporarily disable your wireless network.
  6. Run a speed test. Instructions can be found in the testing your broadband speed article. If your speeds are faster now, follow the advice below.
  7. If your speeds are still slow, try using different cables. This includes a different phone cable to plug your modem into the phone socket, and a different Ethernet cable to plug your computer into your modem.
  8. Run another speed test. If your speeds are faster now, follow the advice below.
  9. If possible, plug in a different modem (with no filter) at your house and run another speed test. If a different modem gives you improved speeds, the first modem may be faulty and may need to be replaced.
  10. If a different modem also gives you slow speeds at your house, please call our Support Team on (03) 8789 4988 for further assistance.

If your speeds improve during the troubleshooting

  1. If your speeds go back to normal when you have just one computer, you can start plugging your other equipment back in, piece by piece.
  2. Wait a minute or two after each device is plugged back in, and then run another speed test to check the speeds.
  3. Always start with any filters or splitters that were used to plug equipment into a phone socket.
  4. If your speed suddenly drops, the cable or device you've just plugged in is probably affecting your speeds. It may be faulty, or it may need a filter.
  5. We recommend replacing a filter or device if it is faulty, or adding a filter to a device if it didn't already have one and it appears to be affecting your speeds.

More information

Why do I need to test a different modem at my house?

Speed issues can be caused by several things, but two of the most common causes are problems with a modem or damage to your copper phone line. Your speed conditions are unique to your address, so modem testing must be done at your property.

If Gtelecom Australia lodges a fault for a copper phone line when there is no damage on that line, then you may be charged an incorrect call-out fee by our wholesaler's fault technician. To reduce the risk of this, we need to rule out as many other possible causes for your speed issue as we can.

If a different modem can give you acceptable speeds at your house but your modem can't, there may be a fault with your modem.

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