Why has my download and upload speeds have been reduced in t

I just received the Report Card from Samknows for the month of March and I have noticed that my download speed has decreased from over 16+Mbps to around 12 Mbps and upload speed has decreased from 1.0Mbps to 0.5Mbps, my line SN margin has gone up from 3.0dB to 13.1dB. For the past 10 years or more I have had a download speed of around 16+Mbps and a SN margin of 3.0dB first with O2 and then with PlusNet when O2 was sold to Sky.
I live around 850m from my exchange and the distance from the exchange to cabinet (2) is 700m and from cabinet (2) to my house is 150m. I do not have any telephone boxes extensions. I have done a line noise test and there is no noise on the line. So I am no wiser as to why this decrease in download speed and increase in SN margin has occurred since February this year and what can be done to return to my original download speed and SN margin.

Any suggestions as to why this has happened?

Past Flash Speedtest Results
Thu 20/04/17 00:08
12.28 Mbps 12.22 Mbps 0.52 Mbps 143.159.xxx.102 PlusNet
Wed 04/01/17 22:51
16.66 Mbps 14.98 Mbps 0.80 Mbps 143.159.xxx.108 PlusNet
Mon 30/11/15 14:25
16.88 Mbps 16.88 Mbps 1.04 Mbps 146.90.xx.105 PlusNet
Fri 06/11/15 13:49
16.91 Mbps 16.87 Mbps 1.04 Mbps 146.90.xx.105 PlusNet
Sat 24/10/15 14:18
17.04 Mbps 16.92 Mbps 1.02 Mbps 87.115.xxx.105 PlusNet

Router stats today 20/4/2017
Uptime: 29 days, 2:31:01
DSL Type: ITU-T G.992.5
Bandwidth (Up/Down) [kbps/kbps]: 651 / 14.335
Data Transferred (Sent/Received) [GB/GB]: 1,87 / 1,10
Output Power (Up/Down) [dBm]: 12,8 / 0,0
Line Attenuation (Up/Down) [dB]: 8,2 / 20,0
SN Margin (Up/Down) [dB]: 8,7 / 13,1
System Vendor ID (Local/Remote): TMMB / ----
Chipset Vendor ID (Local/Remote): BDCM / IFTN
Loss of Framing (Local/Remote): 540 / 0
Loss of Signal (Local/Remote): 64 / 0
Loss of Power (Local/Remote): 0 / 0
Loss of Link (Remote): -
Error Seconds (Local/Remote): 3.024 / 36
FEC Errors (Up/Down): 0 / 0
CRC Errors (Up/Down): 271 / 4.871
HEC Errors (Up/Down): 369 / 145.678
Distance from exchange to house
http://i1304.photobucket.com/albums/s524/scopio1/201...
Speedtest when first joined PlusNet
http://i1304.photobucket.com/albums/s524/scopio1/201...
Speedtest now
http://i1304.photobucket.com/albums/s524/scopio1/201...
Graph when speed dropped
http://i1304.photobucket.com/albums/s524/scopio1/Feb...
Log stats
http://i1304.photobucket.com/albums/s524/scopio1/Rou... 2017 stats
http://i1304.photobucket.com/albums/s524/scopio1/Mar...

Looks likely that higher target noise margins have resulted in reduced sync speeds

A line attenuation of 20dB is more inline with 1.5 to 1.8km cabinet.

The 'loss of' counters suggest something is up, its worth giving the router a complete reboot, power off, count to 10 and back on to see what happens to the connection stats.

I have now done a router reboot as you suggested above and the download speed has remained the same @ 12.3Mbps but the upload has increased to the usual 1Mbps.
The router stats after rebooting
Uptime: 0 days, 0:22:39
DSL Type: ITU-T G.992.5
Bandwidth (Up/Down) [kbps/kbps]: 1.263 / 14.335
Data Transferred (Sent/Received) [MB/MB]: 4,78 / 49,65
Output Power (Up/Down) [dBm]: 12,7 / 0,0
Line Attenuation (Up/Down) [dB]: 6,9 / 19,5
SN Margin (Up/Down) [dB]: 6,0 / 12,9
System Vendor ID (Local/Remote): TMMB / ----
Chipset Vendor ID (Local/Remote): BDCM / IFTN
Loss of Framing (Local/Remote): 0 / 0
Loss of Signal (Local/Remote): 0 / 0
Loss of Power (Local/Remote): 0 / 0
Loss of Link (Remote): -
Error Seconds (Local/Remote): 0 / 0
FEC Errors (Up/Down): 0 / 0
CRC Errors (Up/Down): 0 / 0
HEC Errors (Up/Down): 0 / 0

The only new developing issue that I know about is that BT Openreach has install a new cabinet literally across the road from me although I did see them lay the ducts in the opposite direction to my house so I am wondering if they have swapped my line to this new cabinet and my line now comes the long way round! Would this explain the line attenuation of 20dB?
Position of new cabinet
http://i1304.photobucket.com/albums/s524/scopio1/201...
New cabinet
http://i1304.photobucket.com/albums/s524/scopio1/201...
BT ADSL Checker for my telephone number
http://i1304.photobucket.com/albums/s524/scopio1/201...


Who should I contact if something has gone wrong, PlusNet?

The new cabinet is the FTTC twin for your existing cabinet.

THis is confirmed by the top two sets of numbers in the speed checker that show you could get the full 80/20 service.

Regarding the drop in speed, it's possible something got disturbed while they were running the tie cables from the FTTC cab to the normal one.

Edited by deleted (Fri 21-Apr-17 08:47:05)

Without knowing what the attenuation was previously impossible to comment

Perhaps these previous stats from 2014 can help

Router Stats Saturday 22 Nov 2014
Uptime: 42 days, 7:19:05
DSL Type: ITU-T G.992.5
Bandwidth (Up/Down) [kbps/kbps]: 1.235 / 20.707
Data Transferred (Sent/Received) [MB/GB]: 236,73 / 1,99
Output Power (Up/Down) [dBm]: 12,4 / 0,0
Line Attenuation (Up/Down) [dB]: 10,6 / 19,0
SN Margin (Up/Down) [dB]: 5,7 / 2,8
System Vendor ID (Local/Remote): TMMB / ----
Chipset Vendor ID (Local/Remote): BDCM / IFTN
Loss of Framing (Local/Remote): 0 / 0
Loss of Signal (Local/Remote): 0 / 0
Loss of Power (Local/Remote): 0 / 0
Loss of Link (Remote): -
Error Seconds (Local/Remote): 8.277 / 0
FEC Errors (Up/Down): 0 / 0
CRC Errors (Up/Down): 320 / 10.800
HEC Errors (Up/Down): 674 / 68.606

And After major outrage 30/11/14
Uptime: 0 days, 4:06:30
DSL Type: ITU-T G.992.5
Bandwidth (Up/Down) [kbps/kbps]: 1.219 / 20.527
Data Transferred (Sent/Received) [MB/MB]: 2,73 / 24,64
Output Power (Up/Down) [dBm]: 11,9 / 0,0
Line Attenuation (Up/Down) [dB]: 10,5 / 19,0
SN Margin (Up/Down) [dB]: 6,4 / 3,0
System Vendor ID (Local/Remote): TMMB / ----
Chipset Vendor ID (Local/Remote): BDCM / IFTN
Loss of Framing (Local/Remote): 0 / 0
Loss of Signal (Local/Remote): 0 / 0
Loss of Power (Local/Remote): 0 / 0
Loss of Link (Remote): -
Error Seconds (Local/Remote): 20 / 0
FEC Errors (Up/Down): 0 / 0
CRC Errors (Up/Down): 0 / 20
HEC Errors (Up/Down): 0 / 122
Notice that on these two sets of stats the SN Margin are much lower than at present!
My instinct as to what may have happened is that around the 22nd of February 2017 the BT Openreach engineer/s must have disturbed something in Cabinet 2 which is why the SN Margin and the speed have changed so much from previously and indicated by the SamKnows graph http://i1304.photobucket.com/albums/s524/scopio1/Feb... .

More likely that DLM has intervened, and changed you from a 3dB target SNRM to a 12dB target.

That would account for the change in speed.

Why would DLM do that? Usually because it saw more errors, or more disconnections.

Your attenuation barely changed, so it is not likely that BT engineers lengthened your cable dramatically. They might, of course, have disturbed a joint that is causing (or caused) your error or disconnection issue.

Just spoken to CS and they checked the system and did find that there was a problem and have said that they need to reset something (don't know what) and that it will take a couple of hours to see if that will solve the issue.

I shall wait to see if the SN Margin and download speed go back to what it was before otherwise I shall have to contact them again.

Correct me if i am wrong but....

If you want more speed sign up for FTTC you are currently

G.992.5

on ADSL(2+)

in Cabinet 2

You are not connected to a cabinet.

In reply to a post by ian007jen:

You are not connected to an/the FTTC cabinet.

It may not be live yet of course.