Sync speed dropped from 23 meg to 6 meg

[#1]

Yes my router normally syncs in the region of 23-23 meg, it depended when I synced really, it was a bit higher if I connected midday than at night but a higher sync wouldn't drop over night or anything. I very rarely got any disconnects. Interestingly my router would report the downstream snr margin as 3 instead of 6. I'm not sure why. I know some routers you can choose the figure yourself but mine isn't one of them, at least not without going the telnet route! All I know is the connection had been fast and stable.
I actually had a call from plusnet today, it was a bit embarrassing because they phoned my work and my boss answered and I think he jumped to the conclusion that it was yet another provider trying to get us to switch so he gave the guy a little stick before he realised the call was for me! Sorry if you're reading this!
On the plus side they managed to get an engineer booked for tomorrow morning which I was most impressed with as I only told them when I was free last night!
Let's hope the visit results in good news!
Thanks for all the advice Towman!

[#2]

BT guy is here as we speak but he seems a bit perplexed,  the line seems to be healthy with good stats but on the plus side he has witnessed the LOS happening so at least he has seen for himself there is a legitimate problem.
It can't be my router because I've tried my old back up one and it gives me the same issues, maybe not quite as frequent disconnects but then it has never synced as fast as the new one either.
Seems a bit of a mystery to him!

[#3]

After listening to the line longer he finally detected some intermittent background noise so he's going to come back later with a colleague and go up the pole. Perhaps the recent stromy weather has done something, it does get very windy in this little Welsh valley 

[#4]

Poor bugger is up the pole now in the pouring rain! Interestingly I'm getting a huge amount of disconnections even when not downloading at the moment, could it be related to the rain?

[#5]

The poor guy is still at it after 7 hours, seems like a real mystery case!

[#6]

Well he's just finished and was unable to lock down the cause of the problem,  he's tried putting me on a different pair etc but to no avail. He said the next step will probably be checking the underground line going down to the green box and also a junction box under a man hole in the road.
A bit disappointing but I found him very pleasant and professional and at least I know the issue is still being worked on so it should just be a matter of time.

[#7]

Fair play to him Do hope he gets it sorted. We'll check on the fault for you and see what updates are left on the notes too, our faults team should do that over the weekend but if not we'll pick it up first thing Monday.

[#8]

Quote from: fatdeeman

... it depended when I synced really, it was a bit higher if I connected midday than at night but a higher sync wouldn't drop over night or anything. ... Interestingly my router would report the downstream snr margin as 3 instead of 6. I'm not sure why.

This is fundemental to understanding the dynamics of ADSL DLM.
SNRM is not static, it varies all of the time, which is why constant monitoring via something like router stats is so useful.  When you re-synch, you get the best synch speed attainable at your TARGET SNRM for the then present noise level.  After that, your synch speed remains static (until the next disconnect) and the REPORTED SNRM changes as the noise level rises (night time) or falls (day time) or as infulenced by REIN or SHINE interference.
The fact that the higher synch did not drop over night is likely to be down to less interference / the SNRM staying above zero.
A real shame that the BTOR guy did not find the fault today - this is a good illustration of how difficult fault locating can be, even when you have someone actually trying!!  I hope that the next visit is better.  When you get the next visit, be sure to tell the guy what has already been done - frequently they do not read the historic notes.  Also ask if there is any aluminium in your "copper" circuit!  

Quote from: fatdeeman

The poor guy is still at it after 7 hours, seems like a real mystery case!

That most likely means two missed appointments somewhere else  
HTH
Edited to correct typing!

[#9]

Quote from: Townman

SNRM is not static, it varies all of the time, which is why constant monitoring via something like router stats is so useful.  When you re-synch, you get the best synch speed attainable at your TARGET SNRM for the then present noise level.  After that, your synch speed remains static (until the next disconnect) and the REPORTED SNRM changes as the noise level rises (night time) or falls (day time) or as infulenced by REIN or SHINE interence.

Ahh so when I was seeing SNR figures of 4 or 3 in the evenings and nights that just means it has dropped down from the target 6, that makes sense because it usually said 6 if I ever happened to check in the day time. The sync speed is fixed and you only drop connection if the SNR dips too low at night when there is more noise interference.
This makes sense now because before they changed my target snr to 6 they asked me how much it changed at night!
So if I get a different engineer I can tell him the guy tried all manner of line tests and changed the socket and put me on a different pair all to no avail.
It was interesting because he kept doing something called a quiet line test but it was testing ok but then finally he happened to be doing it at just the time the router lost sync and he said he could hear background noise at the same time but it was intermittent. There was also a strong correlation between the amount of internet traffic and the frequency of the disconnects until it started raining quite heavily at which point it was disconnecting even with little or light use.
He seemed to think the next logical places to check would be the junction box and wiring leading to the green box as I already mentioned. He said at least there's only a few hundred meters of cabling to the exchange lol

[#10]

Hmm well at the risk of tempting fate things MAY have cleared up here. The disconnects were much less frequent after about 5pm and there hasn't been one LOS since 11pm last night, I left my usenet client going all night and not one disconnect and no errors reported by the modem. I'm only syncing at about 15mb but I'm assuming this could be dealt with by resetting the target snr.
This is definitely the most stable it has been since the problem began. I will keep routerstats running and monitor the situation but this looks promising!

[#11]

Hi Fatdeeman,
This is indeed positive news.  I would however (if BTOR think there is more to be investigated / resloved) keep quite about the improvement, less they think they have done enough and close the problem!  15M is a long way short of 24M, which might not be addressed by a SNR reset.  What is your current SNRM?
Cheers,
Kevin

[#12]

Ok I will do that, it would be pretty annoying if it was considered resolved and then it started doing it again the next day!
SNRM is going between 12-13 depending on the time of day.

[#13]

A full set of router stats would be default - please indicate the time the stats were taken.

[#14]

Taken just now (7:51am)
Us Rate (Kbps) 445
Ds Rate (Kbps) 15025
US Margin 26
DS Margin 12
Trained Modulation ADSL2Plus
LOS Errors 0
DS Line Attenuation 3
US Line Attenuation 4
Peak Cell Rate 1049 cells per sec
CRC Rx Fast 0
CRC Tx Fast 0
CRC Rx Interleaved 0
CRC Tx Interleaved 0
Path Mode Fast Path

[#15]

Hi Fatdeeman,
Thanks - this is useful!
Back to expectations - Kits suggests that at your DS attenuation (3dB) you should see 24Mbps at a SNRM of 6dB.  You are currently getting 15Mbps at 12dB.  If we assume that a SNRM reset to 6dB delivers a stable connect, at best this would deliber anothe 2.4Mbps, giving you a best synch rate of approximately 17.5Mbs, which is a long way short of 24Mbps.
I recall from you posings that you are somewhere in (north?) Wales (Deeside possibly?).  Here in North Cheshire it is bright and sunny, so if it is similar near you, I'd consider doing a CONTROLLED reboot of the router - log in to the router drop the PPP session - wait 5 or so minutes then power down the router - get a coffee or some thing else for 15 minutes - repower the router - ensure that the PPP session is back up.  Note with the TG528n after doing a manual drop of PPP sometimes you need to also do a manual reconnect.
The get the new line stats and post back.  If your previous resynch was during the night and I assume a 3dB hit on SNRM due to MW interferance, you might just scrape 20Mbps, which is still 20% short of the Kitz expectation.
Something is still not right here.  What is the latest on your fault ticket?  Have you heard anything further from BTOR?  I think you need to continue running router stats, looking for SNRM spikes / error bursts.  Keep a periodic eye on the error counts, if you see one of them increasing, use routerstats's custom options to monitor that error counter.  Also keep an eye on the bits graphs - the bit swap graph is really useful in pointing to noise issues.
@DCT is there anything from your end to add here?  Has a full copper test been done on this line?  Is the AC balance good?  Has the target SNRM been 'nailled' due to the line's fault history?  The current synch rate is not commenserate with the DS attenuation and resetting the SNRM alone does not seem likely to address the gap - does this point to an issue elsewhere - any thoughts please?
Cheers,
Kevin