Line switch: re-train required?

[#1]

HI Trevor,
You'll have to let us know what happens with the phone fault. Your broadband is definitely with us. Your current sync rate is 9212 but the profile is 6500, That will pick up though if it stays like that.
Jojo

[#2]

Quote from: Trevor

Meanwhile outgoing calls from our phone show up as coming from another number entirely.

Hi Trevor
I had that once when BT did some overnight work at the exchange.
My broadband was OK but the other persons wasn't, so they ran up over £13 worth of calls, on my number/bill, to their ISP trying to sort! 
So make sure you check your phone bill/account.
Cheers Derek

[#3]

Thanks for that Derek. I'll certainly be checking my bill!
The BT engineer came around this morning as promised - the same chap who dealt with the fault last month that started this thread. He had two fixes to make; the first to restore the dial tone, then another to get us back onto our own number. I would give him full marks for prompt and efficient service - albeit moderated by the fact that it was almost certainly finger trouble by one of his colleagues that caused the problem in the first place.
Anyway, after the fix, the line synchronised at 9451kb/s - an all time record. It has dropped back a smidgeon to 9195 since then, but if it settles at anything over 8000 I'll be content.
The main thing is that the DLM hasn't jacked up the target SNR in response to all the disconnections over the last day and a half, so Jojo's SNR reset still has a chance. Hopefully that is a good omen. I'll let the dust settle over the weekend and report back on Monday.
Trevor (typing with crossed fingers)

[#4]

Hi Trevor,
I'm just going to take a look and see if there's anything I can do for you now.
Jojo

[#5]

Hi Trevor,
Your SNR is currently at 6.1dB so that's good. Your profile is 6500, but this won't pick up while your line's dropping. Best thing to do now is leave it as it is and see if it remains stable. One it does, the DLM will lift the profile.
Jojo

[#6]

Sadly Jojo, it didn't last. By 10pm last evening, the DSL rate was still 9159, with a 3hr uptime, which matches with the disconnect you logged for 7pm. However, the SNR had dropped to 2dB.
No great surprise then to see a change this morning, but the size of the hit is very disappointing - SNR raised to 9.5dB (fair enough maybe) but the DSL rate has come down to 7319 (Does 3db usually equate to a 1.8Mb/s speed drop?) So, instead of waiting for the profile to go up from 6500 to 8000, I guess it has now come down to 6000.
As far as I can see, my problems always seem to stem from the SNR dropping during the hours of darkness, with the result that I have to suffer slower speeds during the day in return for greater stability while I'm asleep!
So I guess we come back to the same question - would interleaving help the DLM to tolerate the noise without dropping the synch rate so drastically?
On the positive side, the dial tone is holding up well 

[#7]

Hi Trevor,
There's one or two further drops showing since Jojo posted the above, I suspect that's what's caused the issues there. Could still be a carry over from the work done so worth keeping an eye on rather than raising a fault just yet, though glad to hear the phone is now working. If it continues in a similar vein though it'd probably be worth raising as a broadband fault.
Interleaving will have a minor effect on the sync speed but I'm not sure if it'll make a major difference - to be honest with it set to Auto as it is currently I'm surprised it's not turned itself on. Happy to place an order for that though if you'd like to give it a go.
Those connection records:
<img src="http://ccgi.psmith12.plus.com/visradius/generated/image13115945661164.png" />
Hope that helps, please let us know.

[#8]

Hello Matt,
Thanks for that. My router didn't see a disconnection at 1900hrs on the 24th. The synch speed is unchanged since it took the hit just before 2300 on the 25th and the Uptime is consistent with no breaks since then. One of our machines isn't telling the whole truth! The disconnects on Friday were when the line was faulty and the downtime around 9am Saturday was while the engineer was doing his thing.
Anyway, I might try a re-synch tomorrow morning (or even turn it off overnight tonight). The SNR is still showing as 7.0dB (presumably with a target of 9dB), but it has chalked up another 4000 CRC errors or so in about 33hrs. Not excessive, but more than I would have expected at this speed.
Are you sure that interleaving is set to Auto? It's just that in your post of 12th you said it was disabled. I do see FEC errors on the uplink but not on the down, which seems odd.
Trevor

[#9]

It does seem odd indeed. Just checked on BTs reporting site and it's definitely still set to auto, but showing as off (fastpath) on both up and downstream. Latest update is the 23rd though, which is odder still as that would usually mean that things haven't updated which is why there's no new records.
Still, that's what it's showing at the moment.

[#10]

Okay, well I did turn the router off overnight on Monday. Yesterday morning it connected at 8751kbps with an SNR of 6.0dB. All error counts were zeroed. Here is yesterday's 'diary':
By midday all was well, SNR up slightly at 6.5db, but a mysterious 10,954HEC errors recorded on the uplink (only 421 down).
By 6pm, still all okay, SNR up to 7.0dB, uplink HEC error count increased only slightly to 11,010. Downlink errors: 0 FEC, 1217 CRC, 995 HEC, over 10 hours.
By 9:50pm, storm clouds were gathering, SNR now only 2.5dB, uplink HEC errors hardly changed at 11,046. Downlink: 0 FEC, 2147 CRC, 1741 HEC. Uptime 14hrs.
No surprise then that shortly afterwards it was well and truly clobbered. Here are this mornings full stats:
Uptime: 0 days, 8:44:39
DSL Type: G.992.5 annex A
Bandwidth (Up/Down) [kbps/kbps]: 448 / 6,727
Data Transferred (Sent/Received) [kB/kB]: 0.00 / 0.00
Output Power (Up/Down) [dBm]: 11.5 / 20.0
Line Attenuation (Up/Down) [dB]: 20.5 / 40.5
SN Margin (Up/Down) [dB]: 18.5 / 8.5
Vendor ID (Local/Remote): TMMB / TSTC
Loss of Framing (Local/Remote): 0 / 0
Loss of Signal (Local/Remote): 0 / 0
Loss of Power (Local/Remote): 0 / 0
Loss of Link (Remote): 0
Error Seconds (Local/Remote): 99 / 0
FEC Errors (Up/Down): 34 / 0
CRC Errors (Up/Down): 34 / 4,556
HEC Errors (Up/Down): 11,079 / 1,712 
6727kb/s is an all time low since switching to ADSL2+, all the more frustrating since the line is clearly capable of holding around 9000 during the daytime.
I assume the root cause is the deterioration of SNR during late evening but have no idea how to tackle this. We have an overhead line and a straightforward connection from point of entry to the master socket. No extensions connected. The phone cable doesn't run close to anything electrical inside the house, but does share its poles with the mains electricity supply and a couple of street lamps.
I don't think the SNR drop correlates with the street lamps switching on but I do wonder whether there is a general increase in the current flowing through the mains feed as the evening progresses and whether this has anything to do with it.
Any ideas on how to reduce this SNR drop or to 'ride it out' better would be very much appreciated.
Thanks,
Trevor

[#11]

I think the DLM has worked its "magic", in that your downstream margin is showing as 8.5dB, meaning a likely target of 9dB instead of 6dB. This means, of course, that your downstream rate has dropped, but as the margin has further to go before it drops to a level which will disconnect you, it is much less likely to do so.
When it was set at 6dB, a drop of 4 or 5dB would almost certainly have killed the connection; with it at 9dB, a drop of even 6dB would probably be enough to keep the connection up.
The DLM aims for stability over speed, any time. What needs to be established is what is causing the margin to drop so badly at night. Good luck with that...

[#12]

Hi Trevor
I know it goes against everything we are told about ADSL, but would it be better to switch your router off every night, providing no downloads etc. going, when you go to bed and switch it on 1st thing in the morning. 
Then you would avoid problems of the dropping connection/snr over night.
Before joining Plusnet we used to switch off the router every night, from about 11pm - 8am, and never found it detrimental.
Same exchange equipment - different router, and we had much better sync/download rates etc. than we do with Plusnet and  router on 24/7. (ignoring current line work).
Might be worth trying for a few days
Derek

[#13]

If you do go with the above it's worth disconnecting via the router's interface first - it might take a bit of extra time but if the router is just powered off the exchange sees the disconnection as a fault rather than receiving the request to drop the connection.
It's just another way to make sure the profile isn't dropped.

[#14]

Thanks for the suggestions folks. Tempting though the overnight shutdown approach is, it would really only stand a chance of working during the Summer. In any case, the first time I am a bit late in shutting down, the DLM would presumably leap in and drop the sync rate and immediately drop the profile.
I'm inclined to leave things alone for a bit - I might though start another thread to seek opinions on how much diurnal change in SNR is normal, and what the usual causes are. I suspect thought that, even if the source of the night time noise were located, there's probably little chance of doing anything about it - and I wouldn't fancy my (or Plusnet's) chances of convincing BT that it constitutes a fault. It still would be nice to know what it is though.
Thanks again Matt and Jojo for your help.

[#15]

HI Trevor,
Things are looking much better over the past week.
Jojo