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Message 1 of 12

Smart Hub 2 disconnecting ~every day (DSL Link Down? Noise Margin? DV? DLM? Help!)

Hi, 

Every so often our Smart Hub 2 disconnects - normally overnight, but not always. Comes back within a minute or two, but all devices lose network connection when it happens. Issues have all been since BT cut service on our regular phone line and instead gave us the Digital Voice handsets (DV, which I think is via VOIP) and the Smart Hub 2. No issues like this before (we had normal phones and a TPLink router).

No pattern with anything else coming on in the house (boiler etc), or being used (streaming etc.) - it goes down completely by itself. If it went down overnight I'll usually tell by the fact our TV and Sky box needs to be reconnected to the network in the morning. Frustrating!

I've done some research, and found many similar cases in these and other forums, but haven't found a concrete answer to any, so hoping that putting all the information together, below, will help us work out what might be the underlying issue. All help appreciated!

 

The Technical Logs: taken from the Hub Manager's advanced settings.

At the time of disconnect, the logs always start with a DSL Link Down (here, at 20:06:21 at the bottom), followed by the same string of logs. Note these April logs are identical to the disconnects that happened in Aug, Sep etc.

20:06:57 14 Apr. NTP synchronization start
20:06:56 14 Apr. DSL Link Up: Down Rate=29998kbps
20:06:56 14 Apr. WAN DHCPv6 events: INIT
20:06:56 14 Apr. WAN Sensing Auto sensing Complete
20:06:56 14 Apr. WAN Sensing Auto sensing Running
20:06:56 14 Apr. Success - secondary DNS servers
20:06:56 14 Apr. Success - primary DNS servers
20:06:56 14 Apr. WAN connection WAN2_INTERNET_PTM connected
20:06:56 14 Apr. PPP: IPCP up
20:06:56 14 Apr. PPP IPCP Receive Configuration ACK
20:06:55 14 Apr. PPP IPV6CP Receive Configuration ACK
20:06:55 14 Apr. PPP IPCP Send Configuration Request
20:06:55 14 Apr. PPP IPCP Receive Configuration NAK
20:06:55 14 Apr. PPP IPCP Send Configuration ACK
20:06:55 14 Apr. PPP IPCP Receive Configuration Request
20:06:55 14 Apr. PPP IPV6CP Send Configuration ACK
20:06:55 14 Apr. PPP IPV6CP Receive Configuration Request
20:06:55 14 Apr. PPP IPV6CP Send Configuration Request
20:06:55 14 Apr. PPP IPCP Send Configuration Request
20:06:55 14 Apr. PPP: CHAP authentication succeeded
20:06:55 14 Apr. PPP CHAP Receive success : authentication successful
20:06:55 14 Apr. PPP CHAP Receive Challenge
20:06:55 14 Apr. PPP: LCP up
20:06:55 14 Apr. PPP LCP Receive Configuration ACK
20:06:55 14 Apr. PPP LCP Send Configuration ACK
20:06:55 14 Apr. PPP LCP Receive Configuration Request
20:06:54 14 Apr. PPP LCP Send Configuration Request
20:06:54 14 Apr. PPP: Received PADS
20:06:54 14 Apr. PPP: Sending PADR
20:06:54 14 Apr. PPP: Received PADO
20:06:54 14 Apr. PPP: Sending PADI
20:06:49 14 Apr. PPP: Starting PPP daemon
20:06:48 14 Apr. WAN Auto-sensing detected port DSL WAN
20:06:24 14 Apr. WAN Sensing Auto sensing Complete
20:06:24 14 Apr. WAN Sensing Auto sensing Running
20:06:22 14 Apr. WAN Sensing Auto sensing Complete
20:06:22 14 Apr. WAN Sensing Auto sensing Running
20:06:22 14 Apr. WAN connection WAN2_INTERNET_PTM disconnected.[ERROR_NO_CARRIER]
20:06:21 14 Apr. PPP: Stopped PPP daemon(0
20:06:21 14 Apr. PPP LCP Send Termination Request (User request)
20:06:21 14 Apr. PPP: IPCP down
20:06:21 14 Apr. PPP: LCP down
20:06:21 14 Apr. DSL Link Down: duration was 50736 seconds

 

Line Info: Fibre with BT Halo 3+. Issues have all been since BT cut service to our regular phone line, gave us the Smart Hub 2 and the Digital Voice handsets (DV).

Have put the data rate, max data rate, and noise/attenuation information in bold - the max data rate seems very close to the data rate - could noise be an issue? Not sure how to read noise margin or attenuation info.

Product nameBT Smart Hub 2
Serial number-REDACTED-
Fireware versionv0.35.01.06093-BT (Thu Jun  9 11:13:37 2022)
Board versionR01
GUI version1.74 12_11_2020
DSL uptime4 days 12 Hours 16 Mins 50 Secs
Data rate6.168 Mbps / 29.993 Mbps
Maximum Data rate6.266 Mbps / 38.083 Mbps
Noise margin6.2/6.0
Line attenuation6.6/23.1
Signal attenuation6.6/26.1
VLAN id101
Upstream error controlOff
Downstream error controlOff

 

Wireless Channels:

Smart channel control: On. 

2.4Ghz and 5Ghz signals active - about 6 devices on 2.4Ghz channel, 8 on 5Ghz channel. On 2.4Ghz: about -50db signal downstairs for most devices, -40db upstairs.

Wireless Mode: Mode 1

BT Wholesale Broadband Checker: We're about 300m from the nearest street cabinet down the road.

Screenshot 2022-09-13 at 15.25.12.png

 

 

 

 

.

 

Hope all the above info is of use in working out what the issue is. Any other info you need, let me know. All help massively appreciated! Thanks!

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Message 2 of 12

Re: Smart Hub 2 disconnecting ~every day (DSL Link Down? Noise Margin? DV? DLM? Help!)

I'm a bit confused by your screenshots. Not entirely sure of the relevance of events that took place in April.

Your downstream speed has been capped by DLM at 30M due to instability. Unfortunately, if you are on DV, there is no point in trying a quiet line test to listen for noise on your line.

There is no 'concrete answer' to faults, they are inherently due to difference causes.

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Message 3 of 12

Re: Smart Hub 2 disconnecting ~every day (DSL Link Down? Noise Margin? DV? DLM? Help!)

Thanks for the reply - I chose the April logs as they were identical to the more recent logs and just happened to be the ones I had scrolled to in Excel when making the post. Shows this has been a continuous problem going back many months, with identical logs each time.

DLM (dynamic line management?) capping - is this something that BT handles, or the router? Something I can change?

No quiet line test due to DV - annoying, isn't it... any way round this?

Fully understand 'no concrete answer' to faults in general, but surely this one has a set of circumstances which repeat to cause the same issue roughly every day, and I'm just trying to work out the source so I know how/who to contact to sort it out..

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Message 4 of 12

Re: Smart Hub 2 disconnecting ~every day (DSL Link Down? Noise Margin? DV? DLM? Help!)

The entries in the log stem from one event, a line disconnection and re-connection.

DLM is an automatic process that has taken action due to the instability of your line (frequent disconnections). Unfortunately, it is going to be difficult for an engineer to diagnose the cause due to the intermittent nature. All you can do is report the disconnections and hope the engineer finds the problem.

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Message 5 of 12

Re: Smart Hub 2 disconnecting ~every day (DSL Link Down? Noise Margin? DV? DLM? Help!)

Is there anyone who has some insight as to whether the line noise may be causing the ~daily disconnects, or suggest other possible reasons? Many thanks!

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Message 6 of 12

Re: Smart Hub 2 disconnecting ~every day (DSL Link Down? Noise Margin? DV? DLM? Help!)

Did you actually read my previous reply?

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Message 7 of 12

Re: Smart Hub 2 disconnecting ~every day (DSL Link Down? Noise Margin? DV? DLM? Help!)

Yes.. thank you for the answers but I don't see why your tone is quite as unhelpful as it is? I've done everything I can to provide as much info as possible to prevent people complaining 'we need the full picture', and yet the first thing I get is a complaint about including the info.

"The entries in the log stem from one event, a line disconnection and re-connection." - okay, and as I'm not someone savvy in software, I didn't know that. I thought technical logs could point to the issue at hand, silly me. It seemed they would be useful in diagnosing the issue.

"DLM is an automatic process that has taken action due to the instability of your line (frequent disconnections)" - okay, but what is the action that DLM has taken? That sentence doesn't help. Obviously my line has disconnects - I know that. What does DLM do, and could this be a source of the issue.

"Unfortunately, it is going to be difficult for an engineer to diagnose the cause due to the intermittent nature." - yes, so that's why I've posted this forum question, with all the info at hand, to open this up to more people, as they may have experienced something similar with the same logs and equipment.

"All you can do is report the disconnections and hope the engineer finds the problem." - nothing to be lost by posting this here on the BT help forums before an engineer comes round, who as you say in the sentence before, may not even be able to diagnose it.
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Message 8 of 12

Re: Smart Hub 2 disconnecting ~every day (DSL Link Down? Noise Margin? DV? DLM? Help!)


@hburger206 wrote:
Yes.. thank you for the answers but I don't see why your tone is quite as unhelpful as it is? I've done everything I can to provide as much info as possible to prevent people complaining 'we need the full picture', and yet the first thing I get is a complaint about including the info.
Sorry if I appear to be unhelpful, there is no complaint about the info, it was just an explanation of what it meant.

"The entries in the log stem from one event, a line disconnection and re-connection." - okay, and as I'm not someone savvy in software, I didn't know that. I thought technical logs could point to the issue at hand, silly me. It seemed they would be useful in diagnosing the issue.
They have been useful and the issue has been diagnosed, you have an intermittent disconnection, the source of which can only be discovered by an engineer tracing the fault.

"DLM is an automatic process that has taken action due to the instability of your line (frequent disconnections)" - okay, but what is the action that DLM has taken? That sentence doesn't help. Obviously my line has disconnects - I know that. What does DLM do, and could this be a source of the issue.
DLM action is a an effect not a cause.

"Unfortunately, it is going to be difficult for an engineer to diagnose the cause due to the intermittent nature." - yes, so that's why I've posted this forum question, with all the info at hand, to open this up to more people, as they may have experienced something similar with the same logs and equipment.
How will that help? Somewhere on your line there is an intermittent fault that needs to be traced and rectified by an engineer in exactly the same way as anybody else experiencing intermittent disconnections.

"All you can do is report the disconnections and hope the engineer finds the problem." - nothing to be lost by posting this here on the BT help forums before an engineer comes round, who as you say in the sentence before, may not even be able to diagnose it.

I'm afraid you have unrealistic expectations of the forum, it cannot find the source of the fault for you. There is no magic bullet.


 

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Message 9 of 12

Re: Smart Hub 2 disconnecting ~every day (DSL Link Down? Noise Margin? DV? DLM? Help!)

Thank you, that's useful. So in terms of an intermittent disconnection, is this likely solely a line thing, or is there anything in the above which points to an issue on my end, in the house - something a factory reset of the router, or a noise filter reducer, would help? Or is a filter just for ADSL? Remember this has only occurred since putting the Smart Hub 2 & DV handsets in (they came in the post, no engineer came round or anything), so I don't know if in that process BT did something to my line or not. 

If the issue causing the disconnects is the high noise, is this something fixable by an engineer?

DLM - does that artificially reduce line speed? How does it help?

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Message 10 of 12

Re: Smart Hub 2 disconnecting ~every day (DSL Link Down? Noise Margin? DV? DLM? Help!)

The DSL link down event is a break in the connection between the hub and the cabinet.

It could be anywhere or anything causing the disconnections, it does seem odd that the problem only started with the SH2. It could be the hub itself the cause of the problem.

Don't get too hung up about noise, the noise margin shown in the hub stats is about normal and is different to audible noise. When a line is unstable with either frequent disconnections or a high error rate, DLM reduces the speed of the connection in an attempt to stabilise it.

The filter is just to prevent the broadband signal being heard on an analogue phone. With DV, a filter is not required and will do nothing in any case.

 

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