FTTC - Poor Sync

Hi TB,

I�ve got an interesting problem with my current FTTC connection, I am looking into other options now but that�s outside of this post for the moment.
To give you a bit of background on this issue my line has been running a solid sync at 80/20 for many years now but 29/10/19 my line dropped from 79999/19999 sync to the following:

xdslcmd info --stats
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 1
Last initialization procedure status: 0
Max: Upstream rate = 16265 Kbps, Downstream rate = 58324 Kbps
Bearer: 0, Upstream rate = 16265 Kbps, Downstream rate = 58992 Kbps
Bearer: 1, Upstream rate = 0 Kbps, Downstream rate = 0 Kbps
Link Power State: L0
Mode: VDSL2 Annex B
VDSL2 Profile: Profile 17a
TPS-TC: PTM Mode(0x0)
Trellis: U:ON /D:ON
Line Status: No Defect
Training Status: Showtime
Down Up
SNR (dB): 3.3 6.0
Attn(dB): 15.9 0.0
Pwr(dBm): 12.7 6.8

Here are the stats from the day before:

xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 0
Last initialization procedure status: 0
Max: Upstream rate = 19492 Kbps, Downstream rate = 80936 Kbps
Bearer: 0, Upstream rate = 20000 Kbps, Downstream rate = 79999 Kbps
Bearer: 1, Upstream rate = 0 Kbps, Downstream rate = 0 Kbps
Link Power State: L0
Mode: VDSL2 Annex B
VDSL2 Profile: Profile 17a
TPS-TC: PTM Mode(0x0)
Trellis: U:ON /D:ON
Line Status: No Defect
Training Status: Showtime
Down Up
SNR (dB): 3.4 3.0
Attn(dB): 15.9 0.0
Pwr(dBm): 12.7 6.9

However, since then my line continues to drop in sync speed which is currently on the following:

xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 1
Last initialization procedure status: 0
Max: Upstream rate = 22031 Kbps, Downstream rate = 49148 Kbps
Bearer: 0, Upstream rate = 20000 Kbps, Downstream rate = 50216 Kbps
Bearer: 1, Upstream rate = 0 Kbps, Downstream rate = 0 Kbps
Link Power State: L0
Mode: VDSL2 Annex B
VDSL2 Profile: Profile 17a
TPS-TC: PTM Mode(0x0)
Trellis: U:ON /D:ON
Line Status: No Defect
Training Status: Showtime
Down Up
SNR (dB): 6.1 6.9
Attn(dB): 15.8 0.0
Pwr(dBm): 12.7 6.8

Zen Internet have attempted to T-Shoot the issue but after 9 BT engineers they are unable to provide any improvements. Also, each time BT come out they stay the line is well above average, but they can�t explain the speed loss, one engineer said I would need vectoring to be enabled to return my line to normal. Due to the poor performance Zen have released me from my contract and issued a full refund for the problems.
As of this month I have moved the line over to AA ISP where the line first dropped to 43Mb but has now come up to the above, so I am currently waiting on an update from then about the next steps if any?

So, in a nutshell, I have lost 40% of my total sync speed sync 29th October.

If anyone has any ideas how to improve the current sync speed that would be welcomed, I believe the BT line length is 400m~ from my local cab.

DSL Checker results: https://imgur.com/rTZIeHi

400 metres so good sync for distance. Likely issue is people on neighbouring pairs have upgraded from ADSL to VDSL2 so increased cross talk

I wonder if the OP is on one of the exchanges where BT Wholesale are wanting to withdraw ADSLx?

There have been a couple of reports here of users receiving emails from BT about a free "upgrade".

Not identical, but similar, I'm currently dealing with a BT Business line that is too expensive on it's legacy package, and BT's recommendations are all with VOIP instead of PSTN. Though equivalents with PSTN can be found later in the initially hidden "More" section.

Not sure I follow the reasoning.

https://forums.thinkbroadband.com/fibre/t/4639174-ft... is the post and user is already on VDSL2 so not sure where free upgrades and BT come into, as with AAISP too now

I did wonder if was cross talk but I wouldn't have expected such a dramic fall off, maybe 60Mb but not as bad this. As looking around I see people here with much higher attenuation with faster syncs.

I have been wondering about ordering a new line to see if that would help.

Only that BT are nudging users away from both ADSLx and PSTN. I did say it was only similar, not directly on topic.

The OP could be on a small exchange they want to close, so causing the FTTC upgrades, and in the case I cited it would be Stepping Hill which is large but PSTN is supposed to be gone everywhere by 2025.

I am on a rural small exchange in Essex, oddly my cab does have G Fast but I am too far away.

ADSL/VDSL is RF signalling over wires. If the RF noise floor in the environment increases it will have a corresponding effect on the overall SNR which will affect max attainable sync.

Did any of the 9 visits check anything RF wise as opposed to 'yes our line is carrying DC and a bit of AC up to 4KHz'? ie. did anyone get a radio out and listen for nasty buzzes?

Similarly, do you have any modem stats that could offer a 'bitloading per tone' type measurement or graph, ideally before the sudden drop & after?

I have a current REIN issue in my area coming from a nearby house, who refuse to accept there's a problem etc. Their noisy device takes out a (fortunately) fairly narrow band of frequencies (adjacent tones have a 14bit loading capacity, the affected tones are down to 3) and does affect sync rate.

Edited by deleted (Sat 21-Mar-20 11:49:14)

In reply to a post by kevindb:

Did any of the 9 visits check anything RF wise as opposed to 'yes our line is carrying DC and a bit of AC up to 4KHz'? ie. did anyone get a radio out and listen for nasty buzzes?

Similarly, do you have any modem stats that could offer a 'bitloading per tone' type measurement or graph, ideally before the sudden drop & after?

I have a current REIN issue in my area coming from a nearby house, who refuse to accept there's a problem etc. Their noisy device takes out a (fortunately) fairly narrow band of frequencies (adjacent tones have a 14bit loading capacity, the affected tones are down to 3) and does affect sync rate.

No, not one of them got a radio out to check for buzzes, as they just done the normal line checks. It was just the normal plug the little hand held in and run a normal 5 min test and then a close down test.

Yes, I have over 3 years or so worth of stats as I run a unlocked HG612, i'll dig them out and post them up.

Here are my Bit loading Graphs along with SN, I have shown these to Zen / BT and they didn't seem overly interested.

Before - 29/10/19 - https://imgur.com/iLM0cwn
When the Sync dropped - 29/10/19 - https://imgur.com/UTnXIOI
Today - 21/03/20 - https://imgur.com/tRFjNLj

Also the QLN Graphs also show a consistant drop.

Before - 29/10/19 - https://imgur.com/DOMC6uM
When the Sync dropped - 29/10/19 - https://imgur.com/g2Ui0BH
Today - 21/03/20 - https://imgur.com/IDPa8an

If you need any more graphs let me know.

I'm still waiting on a update from AA ISP

Edited by RSR1 (Sat 21-Mar-20 14:38:41)