Troubleshooting Intermittent ADSL Disconnects

I’ve had problems with intermittent ADSL disconnects over the last couple of years. I have recently solved my problem and a number of people have since asked me for advice on how to troubleshoot their connection problems. I decided to share some general tips for troubleshooting intermittent ADSL disconnects. Some of these tips are specific to my ISP (iiNet) but I’ve tried to keep them as general as possible.

Firstly, you should keep a date time log of whenever you make a change to fix the disconnects. This log is used to verify if your changes have made any improvements (i.e. less / no more disconnects). My ISP provides a web application (Toolbox) that allows me to view my connection / disconnection history so I can review the effectiveness of each change.

Secondly, you should perform a isolation test after each time you make a change. The purpose of an isolation test is to remove all devices from your line to test whether these devices are causing the disconnects. You should do this first before making any change so you have a benchmark to improve upon.

Isolation test steps:

  1. Disconnect all devices from your line except your router (e.g. phones, filters etc.). It’s more practical to do this overnight when you are less likely to be expecting calls
  2. Reboot your router and make sure it establishes a Internet connection
  3. Record the date, time and change that was made to resolve the issue in your log
  4. Allow time to pass for the test to run. If you do this overnight then you can run the test until you wake up in the morning
  5. Plug all your other devices back in to your land line (e.g. phones, filters etc.)
  6. Check your connection history with your ISP to see if there were any disconnects. If there are disconnects then the problem has not been solved. Generally you want to do a isolation test over a few nights for more reliable results.

Thirdly, there are a number of steps you can take to resolve your issue. I recommend that you perform one step / change at a time so you can verify its effectiveness with isolation tests. Note that intermittent ADSL disconnects may be caused by a number of problems and therefore require a number of solutions.

Resolution steps:
1. Perform a initial isolation test first without changing your current configuration. Your router should be the only device connected to the land line. Allow it to connect to the Internet then dial your phone number (e.g. using your mobile phone). Let the number will ring and listen for static on the line. If there is static then you should call your ISP, report these results and request a line test due to noise.

2. Use a short cable (~1-3 metres) to connect your router to your line / wall socket.

3. Factory reset your router and re-enter your ISP connection details. Check with your ISP that your router is properly configured possibly from their FAQ page. Some iiNet specific settings at the date of this posting are:

Username: Append ‘’ to your username (recommended by some users on Whirlpool forums)
Protocol: PPPoE
Encapsulation Method: LLC/Snap-Bridging
Auth Protocol: PAP
Connection: Always on (otherwise it will disconnect when inactive)

4. Change your ADSL router connection mode from ADSL2/ADSL2+ to G.DMT. This will reduce your connection speed but should make the connection more stable.

5. Reduce your connection speed with your ISP if this functionality is provided. For iiNet, you can use the connection speed manager to reduce your speed. e.g. Set your connection speed from “Thrillseeker” to “Standard”, then try “Controlled” and then “Safe” via Toolbox.

6. Replace your ADSL Line Filter. I purchased a filter recommended on the Whirlpool forums which is a ACS 901E2+ ADSL 2+ Inline Filter/Splitter.

7. Call your ISP and let them know what you have done so far. Ask if they can perform a Single Ended Loop Test (SELT) to diagnose your line. This requires you to remove all your devices on your line. Ask them to call you back on your mobile phone to report the results and to inform you when you can reconnect your devices.

8. Test your connection using a borrowed or new router. If there no disconnects during the isolation test with the borrowed / new router then your old router is likely to be the issue. I recommend this step after the above steps because obtaining a router might be difficult / expensive. Your ISP may also be willing to send out a loan router for resolving your problem.

9. Call your ISP and report your findings from your log. Convince them that you’ve perform numerous actions to resolve this issue and request a ADSL / digital line test. This test can identify issues on your line such as degraded copper / high resistance which may be the cause your disconnects. There was a degraded connector / high resistance on my line so this was rectified and I no longer experience intermittent ADSL disconnects.

10. Electrical surges from faulty / degraded equipment and other electrical devices can cause ADSL disconnects through interference. If possible, connect your router to a Uninterruptible Power Supply (UPS) to eliminate this possibility and test for disconnects. If you can’t obtain a UPS then you may need to organise an electrician to check your internal wiring.

I hope these tips have been helpful!