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[whatkatedoes]

Hi all,  I've been on BT infinity 1 for a year, connected fairly solidly @ 40/8, then in April for the hike to 55 (for an extension in my contract, doh)

Suddenly, around three weeks ago, my sync dropped to 42/6 - I've been trying to figure out what the cause is. I *think* it might be line noise.  Scheduled router reboots at 5am can see it return to normal, but only for an hour or so.  I've been dealing with the chat support @ BT, and after wading through all the wifi/try different ports on the BT hub I'm not using, they said they would "refresh my line over 48 hours".

This morning, the max attainable rate jumped back to 57.7 (which is generally what it used to be, up to about 60) but I left the router alone.  Then at about 1145, it dropped back again to 42.  You can see a massive change in the SNRm in the graph here.  Anyone any ideas, 55>42 sucks, but actually the drop from 8.5>6ish really hurts in the upload.  (Sorry for size, scroll right to see the 1145 "hit")



I've tried swapping back to the HH5, filters, cable (carefully, so as not to trigger DLM myself)

Am wary of BT saying to me "welll.. we only guarantee 29mbit on your line anyway.."

[NEXUS2345]

That sounds very much like crosstalk to me. It would explain the dive in SNRM. 

Not much you can do if so. Best thing to do would be to put a DSLStats compatible modem or modem router in and try to pull some stats so that the guys on here can take a look.

[whatkatedoes]

Thanks   I've got billion 8800nl, and it's hooked up to DSLstats, but really the only thing I understand within is the connection speed and SNRm - so if anyone can advise me what to look for, that would be great

[whatkatedoes]

Would my neighbour getting switched from TalkTalk ADSL to BT infinity in the last couple of weeks be a factor in this?

[Dray]

That looks like a line fault. Is your phone line noisy?

[whatkatedoes]

Not to my ears!  It's a cordless, but a decent BT one, and I couldn't pick up anything untoward.

I'm on chat AGAIN just now.  Actually I only went on chat after speaking to @btcare about a missed callback last night, they pointed me back at the chat.. and guess what.. I'm having to go through the whole explanation thing again...

[Dray]

I think you need a wired phone to check properly. I believe cordless phones filter out noise.

You can use the automated checker to see if that can find anything www.bt.com/help/phone

[whatkatedoes]

Shweta: "I can see that there is an fault on the network due to this you are facing this dropping connection and slow speed. We'll need to book an engineer to fix this fault.

I can send an engineer. But if they find the problem is with your home wiring, your equipment, or our network has been damaged within the boundary of your property (by things like trees, building works, corrosion or damp), it’ll cost £129.99."

Hurrah?

We've not changed anything, the only thing changed in our house was the openreach engineer last year coming in to change the wiring a bit, and install a proper faceplate thingie.

[whatkatedoes]

Stats taken from the router around mid-morning when the SNRm was highest, as was the attainable speed:

Max:    Upstream rate = 7124 Kbps, Downstream rate = 57629 Kbps
Bearer: 0, Upstream rate = 6700 Kbps, Downstream rate = 42347 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):        13.8            7.8
Attn(dB):        23.4            0.0
Pwr(dBm):        11.7            3.8

[les-70]

  It looks just like crosstalk.  That drop in snrm  is the same size as I get from next doors FTTC.  Next door alone take about 12Mb/s of my connection, fortunately other cross-talk sources have a smaller impact but still about 4mb/s down with next largest one.  I can tell these sources as they sometimes go on hols or switch off at night.

[whatkatedoes]

Am on good terms with neighbour, so tonight I'll go and have a peek at their router, see what speeds its getting, and maybe even shut it off for a bit to see if it directly affects mine.

I *really* hope that's not what it is

[ktz392837]

I am running at approximately 40% loss on download and 30% loss on upload due to crosstalk.

On the rare occasion it does improve significantly it is for the likely candidates of 2 weeks or 10d or 1 week so it is clear it is cross talk related to other lines.

I would say my disturbers are spread more like 20% + 10% + 5% + 1% + 1% + 1% + 1% + 1% = 40%

[whatkatedoes]

I managed to find some stats from October last year - it doesn't look like my SNRm has changed much?

04 Oct. DSL Link Up: Down Rate=39994Kbps Up Rate=6490Kbps; SNR Margin Down=6.3dB Up=6.0dB
04 Oct. DSL Link Up: Down Rate=31801Kbps Up Rate=9264Kbps; SNR Margin Down=6.0dB Up=6.1dB
05 Oct. DSL Link Up: Down Rate=39994Kbps Up Rate=6400Kbps; SNR Margin Down=6.5dB Up=6.0dB
05 Oct. DSL Link Up: Down Rate=39996Kbps Up Rate=6493Kbps; SNR Margin Down=6.3dB Up=6.0dB
06 Oct. DSL Link Up: Down Rate=34997Kbps Up Rate=6397Kbps; SNR Margin Down=6.9dB Up=6.1dB

As of right now it's 6.4 down, though up has dropped to 5.5 on a 42/6.7 connection.

*having read up on this a bit*

If it *is* crosstalk..  is it worth trying to cajole the OR engineer to try some pair swaps?

[skyeci]

Yonks back my neighbour let me switch his modem off etc as I thought he was the cause of my cross talk. When he was off my snrm shot up and stayed until he reconnected. Managed a pair swap to get away from him. Someone else is now the crosstalker. It may not pay to get a swap as you could end up with a worse one in time etc..

[whatkatedoes]

Found a snapshot log of a previous resync in effect:

Wed 14 Sep 2016  18:19:25,    Noise Margin (dB)= 6.2, Connection Speed (Kbps)= 55000, Upstream NM= 6.1, Upstream Sync= 8004
Wed 14 Sep 2016  18:19:40,    Noise Margin (dB)= 6.2, Connection Speed (Kbps)= 55000, Upstream NM= 6.1, Upstream Sync= 8004
Wed 14 Sep 2016  18:19:55,    Noise Margin (dB)= -0.7, Connection Speed (Kbps)= 55000, Upstream NM= 5.9, Upstream Sync= 8004
Wed 14 Sep 2016  18:20:10,    Noise Margin (dB)= -2.9, Connection Speed (Kbps)= 55000, Upstream NM= 4.7, Upstream Sync= 8004
Wed 14 Sep 2016  18:20:25,    Noise Margin (dB)= , Connection Speed (Kbps)= 0, Upstream NM= , Upstream Sync= 0
Wed 14 Sep 2016  18:20:40,    Noise Margin (dB)= , Connection Speed (Kbps)= 0, Upstream NM= , Upstream Sync= 0
Wed 14 Sep 2016  18:20:55,    Noise Margin (dB)= 6.4, Connection Speed (Kbps)= 42156, Upstream NM= 6.1, Upstream Sync= 6801
Wed 14 Sep 2016  18:21:10,    Noise Margin (dB)= 6.4, Connection Speed (Kbps)= 42156, Upstream NM= 6.1, Upstream Sync= 6801
Wed 14 Sep 2016  18:21:28,    Noise Margin (dB)= 6.4, Connection Speed (Kbps)= 42156, Upstream NM= 6.2, Upstream Sync= 6801