SNR up again!

[#1]

Hi, new here so please be gentle!  Quick history - joined Plusnet in Dec 2011 (BT 21CN exchange) away from O2 LLU due to house move.  To be honest, have had nothing but trouble with my BB ever since! With O2, got used to playing about with the SNR with DMT tool and re-syncing several times a day but no matter how low the SNR went, I always had a connection - and higher sync speed to boot!  Sadly have learnt the hard way that BT Exchange is not so sympathetic to being messed around with, so after a few attempts in January, I have left it well alone.
Everything here is new in the last month - BT master socket, ADSL faceplate, wiring to 2 extensions and of course, a brand new BT2700HGV business router with latest firmware. Now to the problem I still seem to be getting.  I have not had a stable connection for more than 3 days at any one time, with the line being dropped, re-syncing with a higher SNR, lower IP profile and sync speed.  As a result of power cuts on 3 successive days about 2 weeks ago, my SNR had shot up to 16 with an IP profile down to 2000! On Saturday afternoon, after 3 continuous days since the last re-sync, I spoke to one of the Tech guys at Plusnet and he re-set my SNR to 6.  Brilliant - everything went up and I was syncing at 6.7 megs and downloading at 5.7megs on a long line with 51dB attn.  Happy Bunny - until today at 1430, almost exactly 3 days after the last re-sync!
After just one re-sync in 3 days, the BT exchange has decided to up my SNR to 9 (AGAIN) with subsequent drop in sync speed to 5.5 megs, so now downloading at 4.5megs, a drop of 1.2megs!
I was under the impression that one jump in SNR (ie: 6 to 9) would mean a loss of sync speed and download speed of between 600 to 800 kbps. So why have I lost 1.2 megs (double) in one go? As this seems to happen regularly (AND ALWAYS DURING THE DAY between 1230 and 1430) is this possibly a fault at the exchange? I am at a loss to understand it and am even more frustrated by this continual drop in speed. BT quiet line test is just that - quiet!

Am I missing something obvious? Any help please, as I am slowly going mad........
jim:red All Caps in title changed as per Forum Rulemod:end

[#2]

Hello
What about FEC and CRC errors? See here if using default IP address of BT Business hub http://192.168.1.254/xslt?PAGE=C_1_0
Ian

[#3]

Ian, thanks for the suggestion. Errors on my current router are lower now than on any other router I've used during the 11 weeks my line has been live. ES and SES in particular are almost non-existent by comparison!  My current stats are sync speed 5.7, SNR 9.3 and just ran the BT speedtester - IP profile is 4.8 with download speed of only 3.6.  That's 75% of profile and only 63% of sync - where's the 84 to 86% I should be getting?  Cheers.

[#4]

Update for errors.  Collected for 1Day8:18:23.  Can anyone say if these look normal.  Thanks (sorry for the poor layout).

Reset 24-hr int. 15-min int. Last Event
Cum. Seconds w/Errors: 89 21 0 0:03:29
Cum. Sec. w/Severe Errors: 0 0 0 0:00:00
Corrected Blocks: 29511 12967 15 0:00:23
Uncorrectable Blocks: 128 27 0 0:03:29
DSL Unavailable Seconds: 110 0 0 1Day1:10:04

[#5]

Your errors seem very small for a 51dB interleaved line.
I'm not on 21CN so can't really compare as I've no idea (yet) what antics the DSLAM would do to my line.
I gather the 21CN equipment does not really like being 'game played' with the DMT program - unlike the 20CN stuff wich was more stupid.  As you say - leave well alone is the message.
Don't understand why the BT IP setting is not 88.3% of your sync speed if you are on 21CN.
Drops at certain predictable times of the day accompanied by rises in the default target margin are usually from some local switching of something which is causing massive interference on the line......or multiple disconnections over a very short time.  Sometime the Plusnet radius server records all of these, but sometimes it does not catch all 100%.
Perhaps if you had recorded the error levels youring one of the "events" we would be seeing 21million errors - who knows.
Have you tried running routerstats or routerstatslite if they are compatible with your router to see what is happening during the day.  If you set them to sample rate to 15 secs interval it should not miss any re-sync or interference events.
Maybe it is one of these dreaded intermittant faults which come and go.  Mostly OK but all of a sudden everything goes crazy.
The power cuts will not have helped - especially if they are the ones where the substation auto-reclosers try and reconnect the power line a number of times to try and "clear" the fault so you end up with in effect multiple rec-connections over a very short time frame - exactly what the exchange DSLAM equipment will hate.
I'm out of ideas....................

[#6]

Hi Kingsgate15,
I'll look into the possibility of fixing your profile so that each time you resync you'd get 6dB. I'll let you know what I find out.
Jojo

[#7]

x47c - out of ideas... you and me both!! Thanks for reply.
Jojo - that would be brilliant! It's not the disconnects I mind so much as the automatic upping of the snrm.  That really is annoying!  On Saturday night, after the reset by your good selves, I watched the snrm like a hawk for quite a while.  It yo-yo'd between 5.1 down to 4.1 most of the night but still held onto sync. When I was with O2, no matter how many times the router lost sync, it would always reconnect with a 6dB snrm. I would be more than satisfied with that!  Thanks. 

[#8]

HELP!!  Here we go again!        No sooner did I write the last post when my line lost sync - true to form, between 1230 and 1430 as regular as clockwork!
Now on G.DMT Annex A (is that ADSL 1 or 2?) with a sync speed down to 5568, snrm 9dB, attn 47.6 and download speed still at 3.7. 
For this to happen so regularly at this time of day, surely there must be a fault somewhere beyond my router to the exchange?? 

[#9]

I've just been onto our suppliers and had your profile hard fixed. This can take up to 2 hours to take effect but once it does you will resync every time at 6dB

[#10]

Hi Jojo, thanks for that but sadly your suppliers seem to be dragging their feet a little as it has'nt  been changed yet.  Just done a resync and back on ADSL2+ with sync down slightly to 5546 (well, it is evening!), but snrm now 9.2 and line attn 51.  I'll give it another go in the morning and if it hasn't changed by then, I guess I'll be back here!  Cheers for now, Keith.

[#11]

Is the BT Speedtester playing up again?
Oh dear, still only getting 67% of sync (5623) in the bottom speedtest. Tried a Plusnet Thomson (585v8) router earlier and that only managed to sync at 4888 - reconnected the BT2700HGV pretty sharpish! 

[#12]

Well the BT Speedtester seems to be back to normal.  
Any idea why my download rate seems to be capped at 37xx kbps? Nowhere near matching the IP profile, yet this figure keeps coming up time after time no matter how high my profile or sync speed. Something does not add up!  
SNRM still at 9dB.

[#13]

Hi Keith,
I've just raised your profile to 5100 to allow for your new BT profile. The profile change is normally in 2 hours but I will have to leave it 24 before I can go back to them. You should see the speed increase in the next 15 minutes or so.
Jojo

[#14]

Hi Jojo, very many thanks for your help - getting there slowly but surely!  Keith 

[#15]

Just to let you know I'm still working on this hard fix