I got a strange problem with my DSL connection.

When I run a speed test I consistently get an internet speed of 5Mbit/s downstream. I have ran the test at different times and weekdays but it is always the same (and I really mean the same +/-1%).

The plan I got with my ISP is up to 28Mbit/s.

When I look into the modem it says it is connection using ASDL2+ with a bitrate of 20.5Mbit/s. (I got approx 2km to the station)

The SNR is ok (don't remember the exact figure) and if I use the modem's BER-test it tells me 0 bit errors over 60 seconds and 20Mbit/s (it actually says the number of bits transmitted but if I divide it by 60 I get approx 20Mbit)

All this together tells me the station is communicating with my modem at 20Mbit/s.

Is this correct?

If so it means that the 5Mbit/s bottleneck is not between the station and the modem.

My ISP does not listen to this and:

  • They asked me to try with another modem which I did without any difference (bought a new modem which I could return)
  • They asked me to try with different splitter and cable which didn't make any difference.
  • They asked me to try different ports on the modem with no difference (I can transfer files between computers on my lan at 100Mbit/s)

I also did some tests myself and found a strange thing.

I turned of ASDL2+ and used G.bis (or whatever it is called). The modem connected to the station with 13Mbit/s and still 0 bit errors. The strange thing is that the speed test now shows 11Mbit/s to internet.

Can anyone explain this?

The ISP wants to send a technician to my house but say that I have to pay for him if the problem is in my end.

In all cases the uplink is approx 1Mbit/s
The modem is a 3 year old Dlink (but I got exact same numbers with a brand new TPlink)
Only one computer was connected to the modem with a cable during the tests (have tried with different computers and also wireless)

What should I do?

  • The ISP wants to send a technician to my house but say that I have to pay for him if the problem is in my end. So pay it! Usually they only charge if you have done something stupid! The fact that you've gone into this detail and level shows you have a high understanding, I really don't think you'd get charged (assuming your router is plugged into the main point in the house (and you take off the plastic housing and plug direct inside)) – Dave Jan 14 '15 at 8:29

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.