Unexpected transition to ADSL2+/21CN?

[#1]

Hi Support,
Over the last two days I have had 10 forced disconnections despite having had no real issues previously. Looking at my router (Cisco 877) details I see that I appear to be on ADSL2+/21CN and wondered if this had anything to do with it?

DSL Mode:        ITU G.992.5 (ADSL2+) Annex A

(Full stats here)
Judging by some of the posts on the forum I was under the impression that moving onto ADSL2+ was done as a result of either a customer request or you notifying them in advance but neither seem to apply in this case?
Are you able to confirm when I moved onto ADSL2+ and if this might have anything to do with my unstable connection?
For it's worth, for over a year now I've been on the IPv6 trial hence was using a different account - it was only last week that I reverted back to my main account so I don't know if that has anything to do with it.
Regards,
Mathew

[#2]

AFAIK the account used should have no bearing on the ADSL, it' a physical change of equipment at the exchange.
You should have been notified though of impending change (unless you opted out of email notifications).

[#3]

Thanks walker23. Can confirm that I didn't receive notification (but do have them enabled).
Mathew

[#4]

Without request or notification, I too was recently changed to ADSL2+, and experienced similar problems.
I thought I'd give it time and see what transpired, and although it's taken a few weeks, I'm now very happy with a sync of over 5700 on a 53dB 3 mile line - on ADSL1 it was around 4900. 

[#5]

@MJN
Can't see the sync speeds amongst those stats!
@all
Do you have a current email address registered at the Member centre in your Account details?

[#6]

They are listed under speed:

Speed (kbps):             0             8197             0               886

I do have an e-mail address listed, and do indeed receive the occasional e-mail (including bill notifications in case they are related).
Mathew

[#7]

Hi MJN,
I should have gone to specsavers 
That sync speed seems a bit slow for that noise margin (noting your attenuation), suggesting you have quite a noisy line.
First check out if you can hear any audible noise, crackling etc. If so you may have a phone line fault, but you'd need to do some other checks first.

[#8]

No worries. Since you asked, despite always thinking so I did for a moment wonder if maybe they were sync speeds after all!
The sync speed seems to correlate with that predicted by this graph for an attenuation of 43.5dB, or are you saying that my attenuation shouldn't be that high and is thus potentially indicative of a line issue?
What sort of sync speed do you think would be more expected?
I can't hear anything on a quiet line test. The router is plugged into a dedicated socket wired from an XTE-2005 faceplate (with phone extensions wired from the filtered portion of the XTE-2005), no bell wires. I haven't tried the router in the test socket yet as I didn't want to disrupt anything before Plusnet had a chance to chip in.
Digging around I am now aware that there may be issues with the 877 on ADSL2+ however again I don't want to start fiddling (installing the recommended microcode) until formal input has been received on the general issue of the unexpected transition to ADSL2+ because I don't want to start moving the goalposts if anything needs looking at.
Mathew

[#9]

You can't tell what the attenuation "should" be (unless you know the exact cable type and length). One might have hoped for about ½Mb/s more as most predictions are on the pessimistic side. I didn't mean to give the impression you have a fault, just suggested a few checks in case. You may just be unlucky and have a slightly noisier environment than some. However, if there are issues with the 877 firmware I don't think one can draw too many conclusions unless that's resolved. Testing with an alternative modem/router is always handy for comparison.

[#10]

Thanks Anotherone, fully understand.
As mentioned I didn't want to rock the boat and install another firmware until Plusnet have had chance to comment however it's been a few days now since the posting so I decided to to do it anyway. There have been a few resyncs since so it is difficult to tell whether the previous issues were firmware related or not.
I was hoping Plusnet might be able to respond to the questions raised, particularly the one related to exactly when I was 'upgraded' and whether or not the resyncs are related to an inititial training/settlement period or whatever. One concern is that given that I wasn't aware of the transition may mean that the results of any training period (if there is one) might have unduly suffered due to the use of a sub-optimal firmware for ADSL2+.
For what it's worth I don't necessarilly mind my speeds being down by 0.5Mb compared to what one might expect. Far more valuable to me is stability of the connection as sod's law mandates that they always seem to occur at the worst possible time! That, and the fact that my IPv6 tunnel depends on a dynamic DNS script to keep the other end informed of my current IPv4 address and so that is running around like something out of Benny Hill at the moment.
As this thread appears to have fallen between the cracks I might just raise a support ticket with the same set of questions.
Mathew

[#11]

@MJN
I've checked and you were moved over to ADSL2 on the 16th. As you'll probably guess we can't state the precise reason for a disconnection but yes there's been a few over the past few days but not to a level that should impact on speeds at all. Also I've noted that your connections been solid for over 24 hours from my point of view.
<img src="http://ccgi.psmith12.plus.com/visradius/generated/image1342780780228.png" />
I can see service note SN136370648 on the account so you should have been notified by email.

[#12]

Thanks Adam for the confirmation - the 16th does indeed seem to tally with when I first started seeing problems.
As you say, the connection appears to have settled since early yesterday morning (the recommended firmware was installed the night before) and so hopefully all should now be well.
The D/L sync rate seems lower than previously, however the U/L is significantly higher (both compared to that on ADSLMax):

                             DS Channel1      DS Channel0   US Channel1       US Channel0
Speed (kbps):             0             6985             0              1107
Noise Margin:    10.5 dB                          6.0 dB
Output Power:    19.5 dBm                        12.5 dBm
Attenuation:     43.5 dB                         24.0 dB

I'm not at home right now to actual throughput but as mentioned it's the stability I think I value most.
With regards to the e-mail I certainly didn't receive one but I've only got logs going back to the 8th July to positively confirm that. Not that it matters now - the deed (I will refrain from saying damage!) is done.  
Thanks again for your input,
Mathew

[#13]

No worries!
I'm glad we could clear that up

[#14]

Hi Adam,
I'm having to post this via my phone for the reasons discussed below so apologies for the brevity.
Unfortunately things have gone from bad worse as far as stability and throughput of my connection are concerned. Since we last spoke I have seemingly had several disconnections on most days and whilst when the connection is up my speeds can be fairly respectable other times it's hanging on for dear life with barely a packet making it through.
Having enjoyed a rock solid connection for two years now, and only seeing these problems since the 16th July when I was 'upgraded' to ADSL2+ may I ask if it is possible for you to revert me back to ADSL Max (Premium)?
The disconnections endured during the training period were entirely acceptable, however now that that's over I am left with a connection I cannot rely on and one which has an uncanny ability to bail out just when we really need it. Frustrations within the family are approaching boiling point and I am at a loss to explain to everyone why our upgraded connection simply doesn't work.
Regards,
Mathew
Edit 1: In case they are of use, my router stats are currently:

DSL Mode:        ITU G.992.5 (ADSL2+) Annex A
Noise Margin:     8.0 dB                          6.0 dB
Output Power:    19.5 dBm                        12.5 dBm
Attenuation:     44.0 dB                         24.0 dB
FEC ES Errors:   53800                            0
ES Errors:       53705                            0
SES Errors:      53613                            0
LOSES Errors:     1                               0
UES Errors:      53621                            0
Activations:     46
Operation FW:    AMR-E-0.0.026.bin
FW Source:       external
FW Version:      0.0.26
                 DS Channel1      DS Channel0   US Channel1       US Channel0
Speed (kbps):             0             7667             0              1099
Cells:                    0          4242746             0         140353813
Reed-Solomon EC:          0             9987             0                 0
CRC Errors:               0            36778             0                 0
Header Errors:            0            15865             0                 0
Total BER:                0E-0           2306E-6
Leakage Average BER:      0E-0           2531E-6
                        ATU-R (DS)      ATU-C (US)
Bitswap:               enabled            enabled

Edit 2:
My router appears to support some client-side ADSL version control - would any of these be worthwhile trying and perhaps be easier for me to attempt ADSL2+ at a later date?

#dsl operating-mode ?
  adsl2     ITU G.992.3 Annex A and L
  adsl2+    ITU G.992.5 Annex A
  ansi-dmt  ANSI T1.413
  auto      auto detect mode
  itu-dmt   ITU G.992.1 Annex A

It is currently set to 'auto' (and consequently ADSL2+). I thought it better not to meddlejust yet  without your approval in case it might interfere with any diagnostics you may wish to perform at your end.

[#15]

Sorry to sound so impatient with this, but following several disconnections overnight and another this morning I am keen to stay on top of this.
Any comments on my ongoing issues and previous post, particularly the prospect of moving back to ADSL Max (Prem) whether that be through action at your end of with me configuring the router at mine?
Happy to raise a formal support ticket if required, but I figured that the forum seems a far more effective method to discuss the nuances of what's going on here. (I hope that doesn't come across as flattery to get assistance!)
Regards,
Mathew