FTTC line speed reducing

[#1]

I had a similar experience to julianb.  I've had an Unlimited 80/20 fibre connection since June 2013.  Download speeds have always been rock-solid at ~73Mb/s with pings around 10ms.  However, in April I noticed that my BT IP Profile had reduced to 66 and my pings were more than double at 24ms.  I raised a ticket with PN Support to ask why this had happened.  After of a couple of exchanges the issue was put down to the implementation of G.INP on my line.
I have a Huawei cabinet at the end of my road (approx. 100m from my house), but was supplied with a ECI modem by the BT engineer when Fibre Optic BB was installed in 2013.  At the time this was not a problem, but the device firmware does not support G.INP, hence the drop is speed and increased Ping when the G.INP technology was implemented at the cabinet in April.
After reading the OP by julianb I acquired a HUAWEI EchoLife HG612 BT openreach modem and followed the instructions on the Kitz website to unlock the device and upgraded it to the latest B030SP08 firmware which fully supports G.INP.  As soon as I connected the HG612 my BT IP Profile went back up to 77 and Ping came back down to 10ms again.  The PlusNet Speed profile caught up a few hours later.
The output from DSLStats confirms the improved sync speed and that G.INP is active on my line.

Stats recorded 12 May 2015 07:49:24
DSLAM/MSAN type:        	BDCM:0xa44f / v0xa44f
Modem/router firmware:  	AnnexA version - A2pv6C038m.d24j
DSL mode:               	VDSL2 Profile 17a
Status:                 	Showtime
Uptime:                 	11 hours 10 min 1 sec
Resyncs:                	0 (since 12 May 2015 07:49:18)
			
				Downstream	Upstream
Line attenuation (dB):  	11.1		0.0
Signal attenuation (dB):	Not monitored		
Connection speed (kbps):	79999		20000
SNR margin (dB):        	7.9		13.3
Power (dBm):            	13.4		-2.0
Interleave depth:       	16		8
INP:                    	46.00		47.00
G.INP:                  	Enabled		
RSCorr/RS (%):          	0.0000		0.0016
RSUnCorr/RS (%):        	0.0000		0.0000
ES/hour:                	0		0

Regards
Andrew

[#2]

Quote from: julianb

Prior to my FTTC install the estimated download speed was between 70 and 80 Mbps. I estimate the cable distance is about 200m to the cabinet. My FTTC was installed in January and after a couple of days the line speed was 74.8Mbps (from PlusNet portal). I was getting speed tests of 74 down 18 up with 10ms ping, very pleased. However the download speed appears to be gradually reducing. I have not been checking regularly but I noticed last week that the line speed was about 64Mbps. Yesterday it was 57.6Mbps. I did a btwholesale.com speed test late last night and it was below the lower value of the “acceptable range” (that being 60Mbps). The bar was red. I am using the supplied BT modem. I restarted it today, but until then it has been on all the time connected to a UPS. Fortunately the upload speed has not dropped much, as this was the main reason for changing from cable broadband to FTTC. I’m a little disappointed the download speed has dropped below 60Mbps and that the ping times have increased. I realise that many people would be very happy with the speeds I am getting and they are certainly adequate, my concern is the continued gradual reduction in speed. How far below the BT estimated impacted low speed (now 61, was higher) does the sync speed have to be before it would be considered a fault?

Exactly the same thing happened to me and i was on the same connection you had, i had 74 down 18 up and a ping of around 20 for 5 months after taking fibre out.... and 1 month ago the exact same happened to my connection, and plusnet told me its either down to crosstalk or more cusotmers in my area getting fibre.
Im now on 62 to 64 down and 18 up, basicly we were given the best and then it was taken away from us.......... plusnet told me that they nor bt would class my connection as a fault unless it drops to 46 down. Its a total joke because im paying for fibre extra.... im keeping an eye on my speeds and if they drop any futher then im downgrading because its not going to be worth having.

[#3]

Seeing the same issue here
Since joining Plusnet I have always had a connection above 68Mbps - after a line reset in January (due to a compatible VDSL modem screwing my line stats) I had 72Mbps for almost three months. Same thing, I had 72 down 18 up - now I have 52 down 11 up.
Within the last month I have gone from 72Mbps to 63Mbps. Today I am at 52Mbps - with the BT speedtest reporting my IP profile as 55Mbps.
Something has definitely changed within the last month or two on my line, but Plusnet refused to do anything about it, claiming that my Profile was still 72Mbps - even though the BT test reported it as 65Mbps a month ago, and 55 Mbps today.
I've got an old 2012 ECI Type-B modem (which the BT engineer was surprised with) which was supplied by BT/Plusnet.

[#4]

@St3 and @Haffoc:
The most likely reason that atsw and I experienced an increase in latency and decrease in speed was that we were supplied with an ECI modem (by BT Openreach), are connected to a Huawei cabinet and G.INP was enabled. Once we obtained a Huawei modem both ends could use G.INP and performance was increased back to previous levels. I'm now completely happy.
This may apply to you, check your modem and cabinet type (There are resources on kitz.co.uk that can help with this). There are other threads about this.
However there are many other reasons your speed could dropping, described here and elsewhere by others more knowledgeable about it than myself.
It is the sync / line speed or IP profile speed you need to be looking at if you are concerned about the speed of your line between you and the cabinet.  VDSL is very sensitive. Sync speeds are likely to reduce as more users are connected to your cabinet.
My understanding is that unless the sync speed drops below the low speed of your current line estimate (on my line this 45Mbps) it is not considered a fault by BT Openreach. This is the case for all ISPs that use the BT Openreach FTTC service, not just Plusnet. You can see your current estimate at https://www.dslchecker.bt.com

[#5]

I have been down from 72mbps to this for weeks feed up with this......service now roll on when contract ends. ip profile keeps dropping lower.
1. Best Effort Test:  -provides background information.
Download Speed
18.58 Mbps

0 Mbps 65.45 Mbps
Max Achievable Speed
Download speedachieved during the test was - 18.58 Mbps
For your connection, the acceptable range of speedsis 40 Mbps-65.45 Mbps .
Additional Information:
IP Profile for your line is - 65.45 Mbps
2. Upstream Test:  -provides background information.
Upload Speed
4.48 Mbps

0 Mbps 20 Mbps
Max Achievable Speed
Upload speed achieved during the test was - 4.48Mbps
Additional Information:
Upstream Rate IP profile on your line is - 20 Mbps

This test was not conclusive and further testing is required.This might be useful for your Broadband Service Provider to investigate the fault.

[#6]

Quote from: julianb

@St3 and @Haffoc: The most likely reason that atsw and I experienced an increase in latency and decrease in speed was that we were supplied with an ECI modem (by BT Openreach), are connected to a Huawei cabinet and G.INP was enabled. Once we obtained a Huawei modem both ends could use G.INP and performance was increased back to previous levels. I'm now completely happy. This may apply to you, check your modem and cabinet type (There are resources on kitz.co.uk that can help with this). There are other threads about this.

Yeah I have an ECI modem, and it seems that G.INP is enabled. I've got a fault ticket raised (104315610) as well, as a 20Mbps drop over a month and a half isn't normal after 2 years of a pretty stable line.
This pretty much was the state of my connection over the last two years, up until mid April, speeds then dropped to 62Mbps down/14Mbps up and latency increased. Sometime within the last two weeks I've seen another lose of 10Mbps down, and 2-3Mbps up.
Up until April 2015, BT Speedtest reported my IP profile as being 80/20, then 22 April it was 66Mbps, on 23rd that became 65Mbps. Now I have an IP profile of 55Mbps (partially my fault, as I swapped out the cable between modem and socket, and tried to force a resync couple of times)
I'm looking out for an Openreach engineer in my area to see if I can persuade them to do a profile reset and maybe swap my ECI for an Huawei 😉
14/4/2015 7:54 PM GMT  84.93.246.244  66.89 Mb/s  14.62 Mb/s  15 ms  London  < 50 mi  Share
14/4/2015 7:26 PM GMT  87.113.134.242  66.87 Mb/s  16.11 Mb/s  13 ms  London  < 50 mi  Share
26/2/2015 5:55 PM GMT  146.199.109.220  73.15 Mb/s  18.87 Mb/s  1 ms  Nottingham  ~ 50 mi  Share
26/2/2015 5:54 PM GMT  146.199.109.220  73.38 Mb/s  18.86 Mb/s  1 ms  Nottingham  ~ 50 mi  Share
22/2/2015 2:30 PM GMT  146.200.133.162  70.46 Mb/s  16.25 Mb/s  5 ms  London  ~ 150 mi  Share
22/2/2015 2:29 PM GMT  146.200.133.162  70.34 Mb/s  16.08 Mb/s  9 ms  Sheffield  < 50 mi  Share
5/11/2014 1:40 PM GMT  87.115.164.166  71.62 Mb/s  18.85 Mb/s  6 ms  London  < 50 mi  Share
26/10/2014 9:43 PM GMT  87.113.185.64  71.20 Mb/s  17.62 Mb/s  10 ms  London  < 50 mi  Share
25/10/2014 5:05 PM GMT  87.114.17.251  71.05 Mb/s  18.87 Mb/s  5 ms  London  < 50 mi  Share
25/10/2014 5:04 PM GMT  87.114.17.251  71.41 Mb/s  17.48 Mb/s  8 ms  London  < 50 mi  Share
23/10/2014 3:05 PM GMT  80.229.109.160  59.73 Mb/s  13.42 Mb/s  21 ms  London  < 50 mi  - think this was just congestion between me and test server (it was one of the crappier providers speedtest.net use)
20/8/2014 1:30 AM GMT  80.189.63.165  65.29 Mb/s  18.22 Mb/s  1 ms  London  < 50 mi  Share
20/8/2014 1:26 AM GMT  80.189.63.165  66.12 Mb/s  15.62 Mb/s  10 ms  London  < 50 mi  Share
20/8/2014 1:25 AM GMT  80.189.63.165  65.34 Mb/s  16.54 Mb/s  9 ms  London  < 50 mi  Share
5/7/2013 6:06 PM GMT  87.114.170.57  67.34 Mb/s  17.43 Mb/s  16 ms  London  < 50 mi  Share
5/7/2013 6:03 PM GMT  87.114.170.57  69.48 Mb/s  18.83 Mb/s  14 ms  Ealing  < 50 mi  Share
5/7/2013 6:02 PM GMT  87.114.170.57  66.70 Mb/s  17.45 Mb/s  16 ms  London  < 50 mi  Share
5/7/2013 6:01 PM GMT  87.114.170.57  66.41 Mb/s  16.61 Mb/s  14 ms  London  < 50 mi  Share
21/4/2013 2:55 PM GMT  87.112.88.183  70.53 Mb/s  17.36 Mb/s  15 ms  London  < 50 mi