Variable ADSL speeds

In October last year my broadband speed fell from just over 1200 k/bits to speeds around 400 k/bits It stayed at this level for about 6 weeks and then recovered and has remained "normal" until this October when it has again dropped. These results are using the Thinkbroadband speed test. I've just rebooted my router and the results on its log are:- xDSL linestate up (downstream: 1856 kbit/s, upstream: 448 kbit/s; output Power Down: 17.0 dBm, Up: 11.5 dBm; line Attenuation Down: 47.0 dB, Up: 27.0 dB; snr Margin Down: 16.0 dB, Up: 20.0 dB)
I then did a speed test and the results are 806 down and 339 up.

Can anyone explain the discrepancy between the router log and the speed test (they usually agree) and give any explanation for the seasonal drop in my connection speed.

In reply to a post by oldswan:

Can anyone explain the discrepancy between the router log and the speed test (they usually agree) and give any explanation for the seasonal drop in my connection speed.

Unless you are on an LLU package then the actual connection sync speed and your throughput will never be the same due to BT's IP Profiling system.

Are you on an LLU connection?

Looking up the connection speed at http://www.thinkbroadband.com/faq/sections/radsl.htm...

gives 1.5Mbps as your configured speed, or it should be pay a visit to http://www.speedtester.bt.com and it may well be lower, if so it suggests that at this time of year you get more noise affecting your line and disconnects now and then, but does not always reconnect at the higher speed, may something like 1300Kbps occassionaly.

http://www.thinkbroadband.com/faq/sections/radsl.htm... can help improve stability of a line.

I'd be looking at your internal wiring/filtering setup, I've got a 48dB line and sync at 5152kb/s @8.7dB SNRM (in November around 08:00 when I resynced).

Also, your SNRM is very high, can you use DMT or routerstats to twek it down any ?? (best after you've optimised your internal wiring)

Thanks for all of the comments about this issue. The connection speed has continued to drop and today I tried connecting the router directly into the master socket with everything else disconnected, i.e. the router was connected directly to the incoming line and the result on the router log was downstream 3648kbit/s,upstream 448kbits/s output power down 19.0dBm Up 11.5dBm; line attenuation ~Down 47.0 dB Up 27.0 dB snr Margin Down 15.5Db Up 20.0Db. However when I then used the thinkbroadband speed tester my results were 228.79Kbps downstream and 335.58Kbps Upstream. These are the worse speeds ever and I wonder what I should do next?

1856 kbit/s, upstream: 448 kbit/s;

3648kbit/s,upstream 448kbits/s

If you get 3648kb/s in the master with everything disconnected and 1856kb/s normally, I would be looking at my internal wiring. Fault phones, ring wires etc.

As your on BT IPstream the automatic system will take several days to lift your throughput back to as reasonable speed, once it senses that whatever is pulling your speeds down has gone. Sorry with BT it is not instantaneous.

Since I first posted my synch got steadily worse and I was disconnected for up to 30 minutes at a time. Spent ages trying to get Demon to deal with it to no avail. The problem finally came to a head last week when the phone got very noisy and finally gave up altogether. BT tested the line and found a fault which was in a junction half a mile away. One of the cables had corroded badly and finally parted company with the connector. Since it has been repaired my DSL connection has only been down once and my stats are back where they were before all of this started. The Openreach engineer reckons I'm lucky to get 1.4 Mbs as the cable between here and the exchange is a terrible mixture of copper and aluminium lengths joined together where sections of the cable have been replaced due to historic damage.