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ADSL Slow speed beyond the copper?

sandwithbells
Grafter
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Registered: ‎24-06-2008

ADSL Slow speed beyond the copper?

Hi,

I'm interested in anyone's thoughts as to the data below. Mid November the actual connection speed dropped dramatically, we raised a fault with plusnet but before getting anywhere with the plusnet/BTW fault system it appeared to resolve itself. This weekend it has re-appeared...  By my reading of the router data (copied below) the actual ADSL connection is still fine, reporting 899/5083 which is up there as good as this line has ever been.

Today I managed to get the BT system (speedtest.btwholesale.com) to run a speedtest and advanced test (previously I've struggled to get it to load) it reported 1.65 against a profile of 4.8 (copied below). I'm curious as to the meaning of the line "Your DSL Connection Rate: 0 Mbps(DOWN-STREAM),0 Mbps(UP-STREAM)"?

 

Thanks for any thoughts,

Alistair

3 - Firmware version: 7.275.11_F2704N_Plusnet
4 - Board version: F@ST2704N
5 - Mode ADSL
6 - Uptime: 1 days 07:24:59
7 - Data rate: 899/5083
8 - Maximum data rate: 932/5152
9 - Noise margin: 6.6/3.0
10 - Line attenuation: 28.8/53.0

 

Performance Test Results Report
Basic Performance Test -
Time Stamp Latency Download Upload
Sunday 27 December 2020 | 14:58:9 50 Ms 1.65 Mbps 0.96 Mbps
Advanced Performance Test -
Download Test
Download speed achieved during the test was 1.65 Mbps
For your connection, the acceptable range of speeds is 1.2-4 Mbps
Your DSL Connection Rate: 0 Mbps(DOWN-STREAM),0 Mbps(UP-STREAM)
For your connection, the maximum achievable download speed is 4 Mbps
IP Profile for your line is 4.48 Mbps
Upload Test
Upload speed achieved during the test was 0.96 Mbps
For your connection, the maximum achievable upload speed is 0.83 Mbps
IP Profile for your line is 0.83 Mbps
Summary Advanced Performance Test -
Result Message
We were unable to identify any performance problem with your service at this time.It is possible that any
problems you have experienced may have been caused by traffic congestion or by a server responding
slowly. Please visit the Speed Test Guidance if you are unable to understand the test results.

15 REPLIES 15
jab1
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Re: ADSL Slow speed beyond the copper?

@sandwithbells There is definitely something strange here.What has just jumped out at me on a second reading of your router stats is the D/S noise margin - unless I am wrong, and I'm sure one of the even more experienced users on here will tell me, is that with a line attenuation as high as that, you are going to have all sorts of problems at 3dB.

I'm also guessing here, but the BTW speedtest is at times flaky by itself, and your attn/SNR won't be helping. Basically, that report is worth nothing - it is giving erroneous results as a result of the above, and was unable to complete properly, hence the 0.00 DSL connection rate reports.

Three things (1) I assume the low uptime is due to either a reboot carried out intentionally by you OR a DLM induced one? If it was you, don't do too many otherwise DLM will get upset and start throttling you to maintain stability. (2) Can you copy and paste as full a set of router logs as possible? - that may give us a bit more to work on and finally  (3) can you run a speedtest at https://www.speedtest.net/ and screenshot the results so we get all the report.

John
sandwithbells
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Re: ADSL Slow speed beyond the copper?

Thanks @jab1 ,

1) No the reboot wasn't me, not sure of the cause though (see 2!).

2) Any ideas how to get at the logs on this new Plusnet router (2704n)? I can't find anything in the menus or google, and it doesn't accept telnet or ssh.

3)Attached. Are there some detailed results that I've missed?

Screenshot at 2020-12-27 16-30-26.png

Cheers,

Alistair

jab1
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Re: ADSL Slow speed beyond the copper?

The cause is most likely DLM playing up because of your D/S SNR - that should be at least 6dB.

Sorry, I haven't got that router - @Baldrick1 , is it possible?

Nope, all we need is there, and isn't a pretty picture.

I would suggest you get in touch with Plusnet and ask them to try pinning a minimum 6dB profile, and see if it improves anything.

Hope we can get the logs - they are useful tools.

John
Baldrick1
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Re: ADSL Slow speed beyond the copper?

@sandwithbells 

The place to look is in the advanced settings. I'm not sure how much detail you get. To access it point your browser at http://192.168.1.254/expert_user.html 

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sandwithbells
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Re: ADSL Slow speed beyond the copper?

I can't quite believe there aren't logs hidden somewhere but it sounds like Plusnet removed them in their custom firmware. I think I shall perhaps set an hourly cron job to scrape http://192.168.1.254/statsadsl.html which appears to be a hidden page, for a couple of days to see what can be seen from that.

(I should say that the below was after a deliberate restart to baseline things)

Statistics -- xDSL

 

     
Mode: ADSL_G.dmt.bis
Traffic Type: ATM
Status: Up
Link Power State: L0
 
  Downstream Upstream
Line Coding(Trellis): On On
SNR Margin (1 dB): 3.1 7.1
Attenuation (1 dB): 54.0 28.8
Output Power (1 dBm): 0.0 12.6
Attainable Rate (Kbps): 4808 1036
 
  Path 0  
  Downstream Upstream
Rate (Kbps): 4751 987
 
MSGc (# of bytes in overhead channel message): 59 12
B (# of bytes in Mux Data Frame): 148 30
M (# of Mux Data Frames in FEC Data Frame): 1 1
T (Mux Data Frames over sync bytes): 1 4
R (# of check bytes in FEC Data Frame): 0 0
S (ratio of FEC over PMD Data Frame length): 0.9966 0.9959
L (# of bits in PMD Data Frame): 1196 249
D (interleaver depth): 1 1
Delay (msec): 0 0
INP (DMT symbol): 0.00 0.00
 
Super Frames: 0 0
Super Frame Errors: 38970 7
RS Words: 0 1187487
RS Correctable Errors: 0 0
RS Uncorrectable Errors: 0 0
 
HEC Errors: 16497 5
OCD Errors: 9 0
LCD Errors: 9 0
Total Cells: 15279975 3168473
Data Cells: 444831 165321
Bit Errors: 0 544
 
Total ES: 1308 6
Total SES: 1005 0
Total UAS: 1141 52
jab1
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Re: ADSL Slow speed beyond the copper?

Alistair I just typed a reply to your last post - which has disappeared, a long with my reply!!!!Cry

Dunno what's happened there

John
dvorak
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Re: ADSL Slow speed beyond the copper?


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jab1
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Re: ADSL Slow speed beyond the copper?

Alistair - as I thought it would, that stats page proves you should be seeing considerably more speed than you are - around 4.2Mb/s if my calculations are correct. See what happens if you can get PN to push the D/S SNR target to 6.0dB, although I can't see it making that much difference.

A further thought - what type of master socket do you have?

(Thank the stars for autosave - I only had to retype the last line.Smiley )

John
sandwithbells
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Re: ADSL Slow speed beyond the copper?

Thanks I'll raise a ticket on the Plusnet system and see where we go.

The master socket is one of the earlier split face BT ones but unfortunately is upstairs in a spare room so the router is on the end of an internal extension from that. I've optimised that quite a bit over the years so the hit from the extra is minimal. Putting the router in the master socket now makes only a little difference to the ADSL, just causes a headache for the WiFi signal.

Alistair

jab1
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Re: ADSL Slow speed beyond the copper?

Alistair, again, looking at those stats the router is receiving a signal of 4751 kbps - this to me suggests something wrong between the router and your computer. I know I keep asking questions - sorry - but do you have a spare filter to try?

 

EDIT: Can you try with the filter straight into the test socket behind the face-plate?

John
sandwithbells
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Re: ADSL Slow speed beyond the copper?

Tried both those previously to no avail. This morning we are back to 3.4Mbps peaking 3.8 on test which is decent enough, it appears the connection restarted early this morning. SNR 6.4 with a slightly slower connection and the IP profile now at 4.07 from 4.48 with the dodgy connection so we'll see if I can get Plusnet to get the 6db set and cross fingers!
jab1
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Re: ADSL Slow speed beyond the copper?

Looking better. The slightly lower profile is to be expected with the rise in SNR. If you can get PN to pin the level to 6dB minimum, that would be good.

John
sandwithbells
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Re: ADSL Slow speed beyond the copper?

I'll let you know when Plusnet get back to me from the ticket.

(assuming it is in the system properly, the troubleshooter crashed but it did seem to raise the ticket so I commented there...)

Townman
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Re: ADSL Slow speed beyond the copper?

On a 53dB line, the raw synch stats look extremely good. I suspect that the line has good stability (hence the 3dB SNRM) but a high error transmission rate, hence not so good data transfer rate.

The advice from @jab1 is very sound, get the target SNRM raised to 6dB. Whilst this will depress the sync speed it should also reduce the error rate resulting in a better data throughput rate.

Given the length of your exchange line, if fibre is available to you, you might fair much better with FTTC. You are never going to see much sparkle on a 53dB line on ADSL.

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