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Sync speed halved after BT line fault

iciclethief
Grafter
Posts: 26
Registered: ‎31-07-2007

Sync speed halved after BT line fault

Hi,
I've had a pretty much faultless adsl2+ connection with plusnet... until a fault occurred with my line on the 'BT Network' last week.  After receiving appalling service from BT, my line is now fixed.  However, prior to the fault I was syncing around 8500 up, but now it's not getting any higher than 4500 up.  One thing I've noticed that is different now is Fast Path connection is on; this used to be interleaved.
Would the loss of interleaving make such a big difference?  If so would it be possible to switch it back on?
Thanks for listening.
11 REPLIES
Community Veteran
Posts: 4,915
Thanks: 139
Fixes: 25
Registered: ‎14-07-2009

Re: Sync speed halved after BT line fault

Although I am not on ADSL2+, I had a very similar experience a few weeks ago.  As a consequence of a few day's of a faulty line, my noise margin was increased from its normal 6 dB to 15 dB.  It's now about 4 weeks later and so far it has only managed one drop to 12 dB.  My sync rate has recovered to around two thirds of what it used to be. 
Community Veteran
Posts: 38,460
Thanks: 1,031
Fixes: 62
Registered: ‎15-06-2007

Re: Sync speed halved after BT line fault

There are two possibilities - increased default noise margin as ReedRichards  suggests or a capped profile.
You can often tell which it is by looking at the noise margin.
If it is much greater than 15dB then it is almost certainly a capped profile
iciclethief
Grafter
Posts: 26
Registered: ‎31-07-2007

Re: Sync speed halved after BT line fault

The noise margin is 17.4 (it used to be around 6), so it looks like a capped profile.
Is this something that will improve with time?
Community Veteran
Posts: 4,915
Thanks: 139
Fixes: 25
Registered: ‎14-07-2009

Re: Sync speed halved after BT line fault

If you can show that your line is now stable (for a few days) then you can ask Plusnet to set it to retrain.  This will wipe the bad past history and you get to start again with a clean state. 
Plusnet Help Team
Plusnet Help Team
Posts: 13,750
Thanks: 267
Fixes: 78
Registered: ‎27-04-2007

Re: Sync speed halved after BT line fault

iciclethief,
Just let us know if you want us to invoke an SNR reset. This will restart line training, however given the figures you mention it sounds to me like your upstream may be capped. I'll go away and check this and report back ASAP.
Adam.
EDIT: on second thoughts could you drop me your username on a PM? I've not been able to trace your account yet.
If this post resolved your issue please click the 'This fixed my problem' button
 Adam Walker
 Plusnet Help Team
iciclethief
Grafter
Posts: 26
Registered: ‎31-07-2007

Re: Sync speed halved after BT line fault

Hi Adam,
I pm'd you my username.
Thanks.
Plusnet Help Team
Plusnet Help Team
Posts: 13,750
Thanks: 267
Fixes: 78
Registered: ‎27-04-2007

Re: Sync speed halved after BT line fault

Hi iciclethief,
I'm not sure how your upstream got capped when it wasn't capped before. However I've raised an order to uncap it which should go through tomorrow.
If this post resolved your issue please click the 'This fixed my problem' button
 Adam Walker
 Plusnet Help Team
iciclethief
Grafter
Posts: 26
Registered: ‎31-07-2007

Re: Sync speed halved after BT line fault

My speed did increase, but not back to what it used to be.  For the last few weeks my router constantly syncs at exactly 6656 kbps. DMT shows that's about 55% to 65% RCO.  The attenuation is 43.5 and the SNRM is around 10.
Does the never changing sync rate indicate that some kind of banding is still being applied?
Plusnet Help Team
Plusnet Help Team
Posts: 13,750
Thanks: 267
Fixes: 78
Registered: ‎27-04-2007

Re: Sync speed halved after BT line fault

Hi iciclethief,
Yes there's now a 3-6mb profile on your connection, I'm going to speak with one of my colleagues on the faults team for advice on getting this removed so I'll keep you posted.
Adam
If this post resolved your issue please click the 'This fixed my problem' button
 Adam Walker
 Plusnet Help Team
iciclethief
Grafter
Posts: 26
Registered: ‎31-07-2007

Re: Sync speed halved after BT line fault

Thanks Adam.
I notice today that my snr has gone back down to 5.1 (which is nice), but my downstream sync is still never changing from 6656 kbits/s.  Is there anything I can do to help remove the 3-6mb profile?
Cheers.
iciclethief
Grafter
Posts: 26
Registered: ‎31-07-2007

Re: Sync speed halved after BT line fault

I'm pleased to say that my line speed is now back to normal, currently synced downstream at 8918.  Adam, I'm not sure if this is down to you, but if it is thank you.
My BT profile is currently 7150k, but pn is still showing 5500, can this be increased to it's previous value of 9000?
Many thanks,
Carl.