This topic

Banded VDSL Not Resolving

vivoid — Mon, 16 Nov 2020 16:21:47 GMT

Hi All

I'm interested in some input re: situation on my FTTC line.

When installed line was stable at 3db SNR and 39Mbps - this lasted 3 months.

Then something occurred and the line starting dropping almost at 14 day intervals.

Going from

Feb 15th:

DSL Link Up: Down Rate=39999kbps, Up Rate=6536kbps; SNR Margin Down=3.4dB, Up=6.0dB

Oct 11th:

DSL Link Up: Down Rate=22399kbps, Up Rate=5844kbps; SNR Margin Down=10.9dB, Up=6.1dB

During this time the BT hub would appear to lose connection almost daily in the late evening.

An engineer (BT - not openreach) visited and changed the socket in Aug, not much changed.

In september I replaced the modem with an HG612 to check stats and it was quite clear there was REIN interference - SNRM was jumping all over the place (see first pic).

I identified some powerline ethernet adaptors as a possible cause and removed them and the line settled.

An Open Reach engineer in November while fitting a new broadband line identified water in some of the OR junctions and cleaned it out - as this was not on my line, no line reset performed.

Since then the line has been rock solid with little to no SNRM fluctuation, ES per day less than 2 (0.06/hr) however the line remains banded at 25,000 kbps.

I get the feeling DLM has acted over the last year in response to noise and possible water in the circuit.

However now things appear to have cleared and stats have been stable for a while I'd like to get this banding removed and go back to 3DB SNRM and the speed the line should achieve.

Line stats prior to fix.

Line stats with unstable SNR

Stats currently.

Line stats now

I did message @JohnC2 privately, and thanks for your response John - I'm posting this for feedback.

Ideally I'd like a line reset to allow the line to settle back to it's state last year now that things are stable.

Cheers

Re: Banded VDSL Not Resolving

imjolly — Mon, 16 Nov 2020 16:34:04 GMT

welcome to the BT community forum where customers help customers and only BT employees are the forum mods

Have you tried the quiet line test? - dial 17070 option 2 - should hear nothing - best done with a corded phone. if cordless phone you may hear a 'dull hum' which is normal

enter your phone number and post results remember to delete number https://www.broadbandchecker.btwholesale.com/#/ADSL

The 14 day resets are a common problem but are more inconvenient than cause a connection problem as connection normally recovers immediately at same speed and noise margin however the daily resets are more likely to have caused your drop in speed and increase in noise margin. The socket change didn't seem to help - there are no BT engineers just openreach or a sub contractor

your stats show connection time is only 1 day so are you still dropping connection as you need a stable connection for a few weeks before banding is likely to start to remove

Someone may then be able to offer help/assistance/suggestions to your problem

Re: Banded VDSL Not Resolving

vivoid — Mon, 16 Nov 2020 17:18:51 GMT

Hi yes tried the quiet line, all clear.

The connection has been stable for a while, but the night before last the line re-synced and interleaving went from 4 -> 16.

This despite next to no errors for many days and SNR very stable.

Does anyone have any insight into why a DLM resync would occur and increase interleaving (and SNRM from 9 to 10.4 ) with a very stable line (less than 2 ES / day).

Thx

Re: Banded VDSL Not Resolving

imjolly — Mon, 16 Nov 2020 17:30:51 GMT

It appears the DLM is registering errors which not shown by router but sufficient that it caused a reset and an increase in noise margin and interleaving depth to try and improve your line. Until the line problem is solved you are not getting out of banding and if drop outs continue then banding may get worse

Re: Banded VDSL Not Resolving

vivoid — Mon, 16 Nov 2020 17:39:01 GMT

The CAB I'm connected applies any changes at around 3-4AM

The 3.59 AM resync I saw was pretty clearly DLM initiated, but if my connection is showing stable SNRM, sub 2 ES, low FEC - then I'm interested in what the DLM can see that my modem can't ?

Does the DLM not pull error data from the modem throughout the day and apply changes on this basis at around 3-4am?

If anything based on the line stats the status should be green and the DLM should be working to lower SNRM / remove banding / increase speed - not the opposite.

Again, thanks for taking the time and your insight appreciated

Re: Banded VDSL Not Resolving

vivoid — Wed, 18 Nov 2020 12:26:12 GMT

Mods - this connection has been banded at 25000 for a couple of months now - I don't see the DLM intervening to fix it (from what I've read it could be many months if it all) - it's just a little over half of what the line has been stable at previously and right at the bottom of the acceptable range.

A fault was raised in September / Oct and I was explicitly told by BT Phone support - 'we're sending an expert trouble shooter'

The engineer appointment came and went with no visit.

When I queried BT the response was "The engineer came but just visited the CAB" - which I find really very unlikely as I've never had an OR engineer investigate an issue and not even check the ingress to the property.

Would really appreciate an assist on this.

Cheers

Re: Banded VDSL Not Resolving

vivoid — Wed, 18 Nov 2020 12:31:21 GMT

Also - I was told by BT support that they couldn't help further me unless I was using their Home Hub 5 - which imo is unreliable and I have had 2 units fail on me before, both times killing the connection and requiring an OR visit to reset the line.

Ludicrously, BT support also said that they would send an extra Whole Home Wifi disc which "would help the problem".

- of a banded connection? Really ?

Now either they have zero idea how their own product works, or they are pushing the problem away. How is it more cost effective to send a whole home disc rather than just reset the flipping line. I'm baffled.

In any case I'm tired of the lies and disinformation. I know the mods here are the only way this is going to resolve.

Re: Banded VDSL Not Resolving

imjolly — Wed, 18 Nov 2020 12:54:09 GMT

the problem is there is no point in a DLM reset if you are still dropping connection on a regular basis as in no time the DLM would have you back in banding as line appears unstable.

if you can get engineer to solve the connection drops then engineer request a DLM reset having fixed the unstable connection would be best way forward

Re: Banded VDSL Not Resolving

vivoid — Wed, 18 Nov 2020 13:31:31 GMT

Hi @imjolly - The only resync that has occurred has been a DLM initiated resync, has occurred once with the only noticeable change being an increase in interleaving.

Line stats and errors are and were rock solid.

No random drops at all - which implies the line is stable.

I haven't heard anything convincing re why the DLM would resync on a stable line with so few errors, the only way to find out what is going on is for someone with access to the line to take a look.

From what I've read on this site, if a line has interference problems or a fault over many months, it is unlikely DLM will act to remove banding etc without a reset - or if it does it will take a very long time.

You seem to be saying that a DLM resync at 3am implies an unstable line, and this needs to be fixed somehow before a reset ?

How certain are you of this, as there's no way this is taken seriously as a fault by BT phone support and there's not much else I can do having removed any possibility of interference and monitored stats for 8 weeks +

Cheers

Re: Banded VDSL Not Resolving

JohnC2 — Wed, 18 Nov 2020 15:47:53 GMT

Hi @vivoid sorry that you haven't been able to get this resolved. I've sent you a Private Message with details on how to contact the Mod team and we'll be happy to take a look at your connection for you.

cheers

John

Re: Banded VDSL Not Resolving

vivoid — Mon, 23 Nov 2020 15:17:04 GMT

Thanks - details sent !

Re: Banded VDSL Not Resolving

PaddyB — Mon, 23 Nov 2020 15:51:45 GMT

Hi @vivoid,

Thank you for taking my call today. I've run a few checks on your line and your connection looks good.

I've placed a request to have the banding removed and you should start to see an improvement over the next 72 hours.

I'll follow up with your again on Friday to see how the connection is performing.

Thanks

Paddy

Re: Banded VDSL Not Resolving

vivoid — Tue, 01 Dec 2020 11:55:33 GMT

Thanks @PaddyB

I did see something change on Sunday night.

The line resynced and connection speed ticked up to 30000 exactly, but no change in interleaving or any other params.

Line still rock solid with stable SNR, no ES and extremely low FEC errors.

Did the line reset occur do you know, or is this DLM just slowly increasing the banding (from 25000 to 30000) - as 30000 seems like its banded and not the result of a reset.

Cheers

John

Re: Banded VDSL Not Resolving

vivoid — Tue, 01 Dec 2020 11:56:58 GMT

Stats:

Re: Banded VDSL Not Resolving

imjolly — Tue, 01 Dec 2020 12:03:34 GMT

looks like banding starting to release and usually in stages

Re: Banded VDSL Not Resolving

vivoid — Wed, 09 Dec 2020 14:35:07 GMT

Hi Guys.

Pleased to say the line reset occurred and the DLM has progressively :

Dropped downstream interleaving to 8, then 4.

Dropped the SNRM from 10>6>4.5db

Increased down sync speed from 25>30>33>36Mbps

Doubled from the 18Mbs I had in August.

Line is stable with no ES down, and very few up.

For those reading with similar problems, it really is worth monitoring your connection and if you can getting a modem that reveal line stats.

My issue wasn't a fault as such with OpenReach, but with REIN interference from power line ethernet plugs, and other big appliances on the same circuit. Over time this decimated my connection.

I changed the modem to a Zyxel model that could view stats and replaced the cable with a good quality cat5e RJ11 -> RJ45 cable.

I also placed the modem in a faraday cage (a wire mesh box) to further isolate it.

@imjolly @PaddyB @JohnC2 thanks for all of your help - a million times better than the experience I had on the phone.

John

Re: Banded VDSL Not Resolving

imjolly — Wed, 09 Dec 2020 14:38:15 GMT

took bit effort but great result