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DSL service is provided to NCF members with a speed of "up to 6 MB/s download and 800 KB/s upload". This means that it can be less than that speed, for reasons that are out of NCF's control. NCF doesn't want to provide slower than optimal DSL service to members, because it doesn't make people happy.

There are a myriad of factors that affect the actual speed of your DSL connection. This article will attempt to address the main ones.

How much speed are you getting?

This is easy to determine. There are two speeds that are relevant:

  • Your line profile speed, which your modem detects and records in its line stats. Line stats (DSL) shows you how to find out what you modem records the line profile as.
  • Your actual achieved speed, though running a speed test.

Line profile speeds

Why would your line profile be set below the maximum? Because your distance from Bell's switch (central office) or the quality of Bell's lines to your house cannot support more speed. DSL signal degrades with more distance from the switch and distances over 5 km tend to be very marginal for DSL signals. Even closer distances can result in instability of signals and loss of connection at higher speeds. The cure for this is to slow the speed down to prevent this disconnections.

You can get some idea of your distance from the switch and whether distance is an issue for your location, by checking your line attenuation. If the attenuation is high then you are far from the switch and lower profile is probably called for to prevent frequent disconnections.

Why don't speed test results match the profile?

You will rarely see your profile speed as a download speed on a speed test. There is an "overhead" on DSL speeds that means that achieved speeds are usually limited to about 85% of the profile speed. If you have a 6.016 MB/s download profile speed this will mean ideally you should see speed tests turn in results of about 5.1 MB/s. Similarly with upload speeds on a profile of 800 KB/s upload profile expect to see the speed test turning in a result of 680 KB/s.

What if the speed test shows slow speed?

If you are on a profile of 6.016 MB/s and you are seeing speed test results over 4 MB/s in real world conditions that is normal. If you are getting download speeds in the range of 1-3 MB/s then that indicates a problem.

It could be due to any one of a number of problems:

Other users

When you did the speed test were you the only person using your internet connection? Someone else in the house watching a video, streaming audio or playing a game will eat up bandwidth and give you a slow speed test result. Try retesting when you are sure no one else is on line though your modem.


Speeds seen when speed testing via wireless are almost always slower than via ethernet, unless the computer connected wirelessly is very close to the modem. Even with an "N" protocol wireless router a laptop being used for a speed test two floors above the modem will typically see half the expected speeds. With "G" protocol wireless it may be one quarter the expected speed, or worse, if there is interference from other nearby homes.

If you are not getting good speed on your wirelessly connected device then try connecting it via ethernet cable and see if that makes a difference.


Any modem should give comparable speeds on the same line, unless it is starting to fail. One possible sign of a failing modem is loss of speed, especially once it is warned up and has been running for an hour or two.

Even poor ventilation for a modem can cause it to overheat and lose speed.

If you suspect your modem may be the issue contact the NCF office to arrange to borrow a loaner modem to take home an test out your connection.


Running a speed test on an old browser will often turn in slow results, because the browser is slow. Make sure you have the latest version of your browser to ensure that the speed test is not being limited.

Some browsers don't necessarily work well or fast ad can produce slow results, particularly some versions of Microsoft Internet Explorer. Try a better browser:

Operating system

An operating system on your computer that has errors and is breaking down and malfunctioning will not give good speed test results. Microsoft Windows, in particular, breaks down over time and can turn in poor results.

This can easily be tested by running a speedtest on another computer and seeing if the results are different, or booting up another operating system and testing using that. A simple, RAM-based operating system, like Puppy Linux is easy to boot into RAM and, with its included Firefox browser, conduct a speedtest. If the result is faster than normal then operating system is probably the culprit.

Computer hardware

It is also possible that your computer's network or wireless card is failing and producing slow speeds. The easiest way to test this is by using another computer to conduct a speedtest and then compare the results. Different computers connecting the same way and using the same speed test should see similar results.

If nothing works

If none of these hints manages to resolve unexplained slow speed then your next step should be to read Troubleshooting (DSL).

See also

Line stats (DSL) Speed test (DSL) Troubleshooting (DSL)