Why i have lost 0.5mbps?

Im on a TTB LLU ADSL2+ line and have been for years now. I always used to get 7.5mbps speeds, then fibre got enabled at the exchange a few years ago and slowly my speeds increased to around 8mbps-8.5mbps (i assumed it was due to people jumping onto fibre and less crosstalk on the adsl cab)

Anyway about a month ago i created this thread as was getting disconnects during a storm. Since this storm my speed has gone back down to 7.5mbps and no matter what time of day i reboot i cant get it to sync at the same speeds as before the storm. Whether the storm was the cause of this speed decrease i dont know. Maybe just a coincidence.

These are my stats as of now just as i rebooted this morning to test it:

ADSL Link Downstream Upstream
Connection Speed 8823 kbps 1022 kbps
Line Attenuation 38.0 db 18.0 db
Noise Margin 9.00 db 12.0 db

Just a note on those. I have interleaving on and manually set the noise margin to 9db. This was due to having issues years ago and having to up my noise margin to stabilize the line. Those issues have gone now but never bothered to change the noise margin back to 6db (if it arent broke dont fix etc). So although i know the 9db will reduce my speeds, im happy with that as i was still getting 8mbps+ with a noise margin of 9db. Or was until the storm

So any idea what has caused me to loose around 0.5mbps in speed when nothing has changed my end? Errors etc on the line are minimal and quiet line test is clear. Dont have any stats from my router before the storm but sync was around 9300kbps-9800kbps. My only assumtion is there has been an increase in adsl connections on my cab so crosstalk has increased.

Edited by bobble_bob (Sat 07-May-16 08:34:59)

It needn't be anything to do with FTTC. When I was on ADSL2+ simply the chap across the road, fed from the same pole, turning his router on an off had the same effect on my line.

As I ran RouterStatsLite at the time I could see my noise margin alter at the times he switched on and off. A re-sync always reflected the state of his modem at the time.

Over the years since July 2007 when my exchange first got adsl my speeds (and synch) have varied from 6.5 Mbps down to about 5 Mbps and recently back up to 6 Mbps, it's just the nature of the beast (xDSL)

HR faults just develop slowly and cause your synch speed to drop; these HR faults would not be able to be found and repaired by OR, just be patient and maybe the fault will recede or increase by enough to cause a voice fault that OR would be able to find and repair.

I find I lose 0.5mbps sync between summer and winter. In winter I get 18mbps @ 1.5db SNR and in summer its 17.5mbps. I have just observed the drop in the last few days with the warmer weather coming. Could this be it for you?

I dont think so. Ive had a good few years of higher sync. Unfortunately little i can do about it other than changing my targer SNR. Nothing my end gives cause to the reason why

It could be anything. Could even be something like Openreach have changed out a section of faulty cable and replaced 0.63mm with 0.5mm.

You'll probably never know.