Downstream margin reduces with time

I've had a rock steady connection on ADSL MAx for a few months now at 1856kbps. Over the last few nights my downstream margin drops 1dBA every hour until the modem eventually resynchs to a lower connection speed.

Anyone any ideas please?

Stats? (line attenuation, noise margin, etc.)
Also how & where is your router connected?

Stats are as follows:

Modem Status
Connection Status Connected
Us Rate (Kbps) 448
Ds Rate (Kbps) 1760 (was 1856 2 hours ago)
US Margin 17
DS Margin 8 (was 17 2 hours ago)
Trained Modulation GDMT
LOS Errors 0
DS Line Attenuation 60
US Line Attenuation 31
Peak Cell Rate 1056 cells per sec
CRC Rx Fast 0
CRC Tx Fast 0
CRC Rx Interleaved 1
CRC Tx Interleaved 0
Path Mode Interleaved


DSL Statistics
Near End F4 Loop Back Count 0
Near End F5 Loop Back Count 0

Router connnected to ClarityADSL filtered faceplate, connected by cat5 network cable, supplied by Clarity, to NTE5 faceplate.

Edited by Hartside2 (Tue 10-Oct-06 22:06:42)

Is your 'phone line supplied using poles and overhead cables?
Also, how long is the CAT5 cable from the master socket to the router (if quite long, try direct into the master), and try the 'test' socket inside, just in case you've a dodgy filter.

I would say your problem is interference from AM radio stations (hence, the noise margin is falling overnight).
If it is, there's very little you can do (maybe try a different router, just in case).

The problem will only get worse now that winter is approaching, and we have fewer hours of daylight.

My phone line is supplied via an overhead cable from a pole. The CAT5 cable length will be about 10m from NTE5 to ADSL faceplate, then there is a 2m cable from the ADSL faceplate to the Route.

Just had a thought - new boiler fitted over the summer with a wireless link thermostat. I wonder if there's interference from this as everything has been fine for months?

In reply to:

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Just had a thought - new boiler fitted over the summer with a wireless link thermostat. I wonder if there's interference from this as everything has been fine for months?

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Anything in the vicinity which changes at about the time a fault appears must always be considered suspect until it can be eliminated. It is very probable that it won't have had much effect until the last week or so.

It ought not have much effect uniess either end of the link is close to the router or any of the cable carrying the ADSL. Try turning it off for a while and see if that helps. If so, then you need to look into moving the detector - I doubt whether moving the boiler controller is feasible. If you can't find a suitable location and you are convinced that it is the thermostat, you may have to consider a wired one.

I have a wireless thermostat and it does not affect my ADSL, and I would not expect it to, because they work on 432 MHz, which is way above anything used by ADSL. I would suspect the actual boiler though, because the ignition systems on those can give problems. It's quite an easy thing to rule out, though.

My prime suspect is the changing seasons, and less daylight affecting the ionosphere.