very poor service and a warning re 21cn "upgrade"

[#1]

>:(having been advised that my exchange would be upgraded to 21cn i asked for the likely effects of such a change. i was advised that i could expect a slight speed improvement and possibly more drop outs. i was told that i did not have to update.
after a fault occurred on the line the "upgrade" was automatically implemented and for the last 8 weeks it has been a nightmare with speeds now 60% down and the comments/support from the help and support being both inaccurate and misleading.
i am left after 8 miserable weeks being told there is no more they can do and that due to my line length i must live with the downgrade.  a change back to the old exchange is NOT POSSIBLE. my speed is now 500kbps whereas i used to get for over 5 years an average of 1150kbps. had i known that 21cn is poor on line lengths over 2 miles i would have insisted on remaining with the old exchange.
i now have a complaint raised with plusnet re misleading and inaccurate information but they have failed to respond to even this.
i would like to WARN others that the 21cn is ONLY an upgrade to speed if you have a short line length - as plusnet should do.

[#2]

That's not a good generalisation about 21CN on line lengths over 2 miles, it does depend upon line condition and general noise levels anywhere along the length of the line. It sounds like your fault has been ping-ponging about between several agents who may not have grasped the crux of what's causing your poor connection performance.
Can you post the following information - ADSL Line stats from your modem/router (see here - select FAQ's and Troubleshooting and View More on your DSL connection, or here , for guidance if you don't know how to get them), the Results from a BT speedtest (diagnostic) and your Current Line Speed (login required).

[#3]

have lots of info from my router, unable to copy in but main details are:
attainable rate 1396kbps
rate down 960kbps
rate up 416kbps
SNR  6.1dbs down
SNR 5.1dbs up
attn 72.5dbs down
note prior to 21cn upgrade snr varied from 3dbs to 0dbs depending on weather but no one believes this
also copper line to connection box ( half of total 2.3 miles to exchange) has been replaced, i watched them! ( about 2 years ago)
attainable rate varies with time of day, weather and loading between 1080 and 1400kbps
bt speed test:
d/load 544kbps
u/load 349kbps
ip threshold 850kbps down, 450kbps up
speed bt qos test 523kbps
bt beta 460kbps down, 370 up, ping 47ms
speedtest.net 570 down, 370 up, ping42ms
bt engineers say line is excellent, plusnet say ?
bt engineers say likely exchange problem, plusnet claim to have requested a lift and shift but bt refuse!
have tried 3 routers with/without broadcom chipset all different makes. the netgear without adsl2+ gives highest speed but most errors, tp link and zoom give similar speed and errrors
the router is connected directly to the incoming line, filter(s) make no difference
neighbours with identical line ( again plusnet will not accept) have all had a small improvement in speed with varying isp providers, orange/bt, no one else on plusnet, there are only 7 houses  on the line from the connection box!
if you need any more specific info happy to provide, otherwise thank you for your interest and support

[#4]

managed to get tp link router info into a word file will try and copy in:

Mode: ADSL_G.dmt.bis
Traffic Type: ATM
Status: Up
Link Power State: L0

Downstream Upstream
Line Coding(Trellis): On On
SNR Margin (0.1 dB): 61 51
Attenuation (0.1 dB): 725 447
Output Power (0.1 dBm): 0 129
Attainable Rate (Kbps): 1420 416

Path 0 Path 1
Downstream Upstream Downstream Upstream
Rate (Kbps): 960 444 0 0

MSGc (# of bytes in overhead channel message): 59 10 0 0
B (# of bytes in Mux Data Frame): 30 63 0 0
M (# of Mux Data Frames in FEC Data Frame): 4 1 0 0
T (Mux Data Frames over sync bytes): 1 1 0 0
R (# of check bytes in FEC Data Frame): 10 0 0 0
S (ratio of FEC over PMD Data Frame length): 4.0 4.5309 0.0 0.0
L (# of bits in PMD Data Frame): 268 113 0 0
D (interleaver depth): 8 1 0 0
Delay (msec): 8.0 1.13 0.0 0.0
INP (DMT symbol): 1.19 0.0 0.0 0.0

Super Frames: 18152200 538075 0 0
Super Frame Errors: 0 0 0 0
RS Words: 294973264 0 0 0
RS Correctable Errors: 1681465 0 0 0
RS Uncorrectable Errors: 80888 0 0 0

HEC Errors: 4294967295 8794 0 0
OCD Errors: 0 0 0 0
LCD Errors: 0 0 0 0
Total Cells: 667841720 516720 0 0
Data Cells: 8339319 4784 0 0
Bit Errors: 0 0 0 0

Total ES: 19120 4294967293
Total SES: 19 0
Total UAS: 152 4294967240

[#5]

Can you tell us what the uptime was for those stats?

Quote

.....filter(s) make no difference

Do you mean changing filters makes no difference?
Do you have any extension sockets and any phones , sky boxes etc connected to the line - are they all connected via filters?
That 2.3 miles to the exchange - is that as the crow flies or the route taken by the line or info from the BT engineers?
We don't want your speed to get any worse by any increases in noise margin etc. so I'd recommend you do the following from now on when you do anything that may involve a loss of sync (eg. swapping modem/routers, filters, cables or sockets etc or just a need to switch off) -
Login to the modem/router interface, look for the details of your PPP Internet session, probably where you enter your Broadband username and password. It should show you as connected and a clickable "Disconnect" or "Drop session" button. Click on it and wait until it shows you are disconnected (you may need to refresh the page, not usually). Then power down the modem/router and wait a few minutes before disconnecting from the line. Make any changes, after about 10 minutes, power up. You may need to login to the modem/router and click "Connect" to establish the PPP session.
This procedure helps to prevent the exchange DLM from thinking you have a dropping connection. Don't do this more than about 5 times in an hour, then leave it alone for the rest of the day. Use this procedure instead of a reboot.
You can use the Disconnect/Connect routine without the power down (no loss of sync) to do a Gateway hop.#
In normal circumstances, if you don't already do so, I'd recommend you keep the modem/router on 24/7.
Sometime in daytime tomorrow can you try one of the other modem/routers and post the stats from that.

[#6]

From looking at those numbers, it might be an idea to have a lower upload cap to help with download stability.

[#7]

I was going to suggest asking for the upload to be capped but after another sets of stats from one of the other modem routers so as to compare like with like.

[#8]

The stats posted suggest the line is training in ADSL2 mode (G.dmt.bis) not ADSL2+.
I would suggest checking the modes that the router/modem allows, adjust as necessary and try a resynch.
cheers
Graham
Edit: per post below 

[#9]

I referred in another thread about using the term gateway when referring to modem/routers - it's confusing.
Again, locking the connection to ADSL1 (at the exchange) may also be a way to go but after we have compared like with like.

[#10]

As far as I am aware, ADSL2 tries to pack 12Mbit into the same frequency range as ADSL1. I would expect this to perform rather badly on a long line, perhaps worse than ADSL1. Forcing the sync to ADSL2+, with its extended frequency range, may just give the breathing room required to at least get back to the OP's sync rate of 1150.
cheers
Graham

[#11]

It will be very line dependant, and in any event I don't think you can force ADSL2+ if the MSAN says no! And really there is no point because the extra (higher) frequencies just don't get to the EU. (see here for example, another very long line). Forcing ADSL1 from the exchange end may do the job, but as I've said let's compare like with like first.

[#12]

Hi,
I had issues when the exchange I'm connected to switch to 21CN. After much testing Jojo suggested switching my connection to ADSL1 on 21CN, since then the disconnects have stopped. I also think my Line Speed has been fixed at 2.5Mb as I always maintain this speed.
In the past I also used to have higher speeds
ADSL Link Downstream Upstream
Connection Speed 3776 kbps 448 kbps
Line Attenuation 55.0 db 29.0 db
Noise Margin 4.8 db 18.0 db

ADSL Link Downstream Upstream
Connection Speed 3201 kbps 448 kbps
Line Attenuation 55.0 db 28.0 db
Noise Margin 12.9 db 21.0 db
If the noise margin is lower than the current level my line becomes unstable. I'm more bothered about a stable connection rather than a fast one.
Dan.

[#13]

thanks for all the feedback, found some of it a bit confusing. will add more info as follows:
uptime is currently running at 10days 16hrs, so believe it has "stabilised".
modem/router is connected 24hr and never turned off
modem connection to line is via master skt at point of entry to house, master skt faceplate is only filter on the adsl line. only other connection is telephone line (one off) on an extension skt. it currently has one filter on the skt o/p to the telephone. have tried different filters on all lines and had the adsl line connected directly to the line behind the master skt faceplate.- no difference.
was not aware that i could "give up" upload speed to improve download speed, is this really possible? i would be very happy to do this.
distance to the exchange - do not know how accurate this is, i suspect its as the crow flies but route "should" be straightforward according to bt engs and road layout. bt gives distance as 3.8km
had a good look thro my tp link router pages and cannot find anything to let me disable conn. will continue to explore this and if successful will get stats for my zoom router and post them.i can confirm that the stats from th zoom were pretty much identical inc the upload speed which is always static. it was interesting that my non adsl2+ netgear router gave improved speed at the expense of errors i belive this to be due to the slightly different operational frequencies?
confused by the refs to adsl1 and adsl training mode - any further explanation appreciated.
i have also received a personal message from chris pettit at plusnet tech support asking for my home phone no. chris if you are from plusnet then you can access my fault ticket ref 53533734 for details

[#14]

Yes, Chris Pettitt is a very helpful Tech Support chap from Plusnet who has made several posts on the forums and will no doubt access your ticket now he's got the number. I'm guessing because he was maybe trying to trace your account to run some line tests and your forum registration usually leads to the correct information but may not have done so this time.
OK, capped uploads - some users have reported stability issues when having the upload uncapped, so that is always worth considering. It can sometimes come at a small expense to download speed if more bandwidth is allocated to upload, so if you don't need fast upload speed it may as well be capped.
The Netgear may have had a slightly different bits per tone allocation when you tried it which may account for the different errors. You can update the firmware to make it ADSL2+ compatible. I'll see if I can find the links. It wouldn't be a bad idea to check that you've got the latest firmware on each of your modem/routers.
If you post your TP-Link model and version, I'll see what I can dig up - if you've had a stable line for a good period then 1 or 2 swaps without the Disconnect procedure shouldn't cause a problem. Pull the power plug first though and wait a few minutes. Swap to your Zoom as soon as convenient but do it at least a good hour before dusk (but see below first).
On 21CN you can be set at ADSL1 mode at the exchange which can give a more stable connection as it won't event try to use the higher frequencies of ADSL2(+),. so again something to consider.
If that 3.8Km is based on a line test and the cable is all 0.5mm copper you should be around the mid fifties for line attenuation and getting at least 3 times the speed you've got. Try going via the road route and see what distance you get yourself.
Your extension socket  - before you swap modem/routers have a look at the wiring connected to the back of the extension socket (not the master at this moment so as not to disturb your BB connection) and tell me what colour wires there are and what terminal numbers they are connected to.
We can get a bit more technical (we may have to anyway) but that rather depends on whether you'd like to, or whether you'd rather take the suck it and see approach first.  If you'd like to get a bit more technical I'll PM you a bit of info.

[#15]

thanks for the update:
have checked the tp link and zoom routers have the latest firmware. but will double check this, both are recent acquisitions-  models nos for interest are tp link: TD-W8960N ( tried the later 8961 first but it appeared faulty so replaced with the supposidly more stable older model) and the Zoom is an X7N. Prefer the TP link, appears to run much cooler and the info from it is better. Both have the broadcom chipset which from research appears to be the best for long distance. Aware the Netgear can be updated but it was getting fairly old.
will try and gather other info re wiring and exchange distance over next 24hours. Just out of interest - there are other unused extensions on the phone line, would it be a good idea to disconnect these if possible? or maybe disconnect all extns and run phone and adsl from the master skt?
I should probably add that i am not a complete pleb regarding computers and transmission lines. i used to design computers and did transmission lines in some depth at college! but that was all some time ago!!! the software i wrote was far simpler than anything today and i have to say the size and complexity of todays operating systems and switched networks leaves me cold!!! So happy to get a bit more technical but i depend heavily on broadband so need to keep some connection going and not mess things up. ah the joys of living in the country as my friend in London keeps reminding me....