Intermittent VDSL disconnections (Possible REIN?)

Hello.

First post here. I'm hoping to get some suggestions on how to diagnose disconnections on my FTTC VDSL service, please. I want to rule everything out that I can before my ISP orders an Openreach SFI engineer with the risk of a £220+ bill if they can't find a line fault.
I know information is important when trying to rule things out, so bear with me as I dispense the lot.

ISP: Uno
Service: 80/20 FTTC (normally 70Mb down, 15Mb up on BT Wholesale Speedtester)
Modem: BT Openreach Huawei HG612 (possibly 1st version, not unlocked, no firmware updates since installation in 2009)

Fault:
- From 10th or 11th May, I've had frequent and intermittent disconnections. The dropouts last for 10-13 seconds, then reconnecting. Usually reconnects on first attempt but sometimes the modem takes 2 attempts to reconnect.
- Disconnections are anywhere from 90 seconds to 4 minutes apart, but most commonly around 2 minutes.
- There have been a couple of periods of extended uptime, but no rhyme or reason to it (have had both mid morning and late night).
- Disconnections continued throughout the weekend.
- When my connection is up for long enough for me to carry out a speed test, my speeds have dropped to 45Mb down, 10Mb up.

Checks carried out so far:
- Eliminated router as problem by connecting 4 different computers (2 x Mac, 2 x PC) directly to modem and connecting through PPPoE.
- ISP say they can't see a problem, escalated it to Openreach who say they can't find any issues on the line remotely.
- I have tried unplugging various bits of electrical equipment around the house, plus I have used an AM radio tuned to 612Khz but I cannot find an obvious source of interference.
- Modem is plugged into a double socket in it's own, both are less than 300mm from master socket.
- Have spoken to next door neighbours either side to see if they have problems but they all have cable broadband with Virgin. They also haven't bought any new electrical items in the past week.

Next planned checks:
- Try another modem (I have ordered a HG612 3B from eBay seller) to establish whether my modem is faulty
- See if neighbours will let me 'scan' their houses with my radio

Background:
- I have had FTTC since BT's first trials in 2009 with no broadband problems at all until last week.
- Semi-detached house on suburban street.
- Telephone line fed overhead from pole. Pole and cable were renewed less than 10 years ago.
- I don't know line distance but cabinet is physically less than 500m walk away.

Could anyone offer suggestions on what other steps or checks I could or should take to isolate the cause of this fault, please?

Thanks in advance for any helpful thoughts.

Edited by deleted (Wed 17-May-17 20:52:50)

I'd start by disconnecting your internal wiring and plugging the modem into the master socket - or, even better, the hidden test socket assuming you have an NTE5 (which has the effect of disconnecting your internal wiring if the NTE5 is correctly wired). Though the socket you're using is physically and presumably electrically close to the master, if there is other internal cabling that might present as a bridged tap and/or a conduit for noise to get into the system.

Get DSLStats installed on a PC and leaving it running - you will need to flash te modem with unlocked software to allow DSLStats to monitor the stats And you could have te information uploaded to an online account at https://www.mydslwebstats.co.uk/

Once you have data and several drops, look for issue just before - does the SNR change greatly, what value does it return to ...

Thanks for responding, David.

I had intended to use the test socket as part of my initial investigations but I couldn't find a micro filter. You have reminded me that I hadn't done this, so I found the filter this afternoon and tried it. Although, the only other socket is a former secondary master socket which is now an extension backwired from the downstairs (and now only) master which is an NTE5C with mk4 faceplate.
However disconnections continued but after about an hour, the line seemed to enter a stable period and I didnt see any disconnections for a number of hours. I decided to put the faceplate back on but the line is still stable, so I'll have to see if it lasts tomorrow.

My line speed has halved in both directions so I'm now getting 35Mb down and 7Mb up but I presume this is down to DLM. If the line is stable from here on out then either the source of interference has stopped or moved on, or would it suggest that there is actually a problem on the line somewhere?

Thanks for responding; once the other modem arrives, I'll feel happier about unlocking one of them in case I end up bricking it or something; having software monitor and log the line is the best thing we need, especially given the nature of the fault.

Thanks

Fine to be cautious ... I have heard of very few that have gone totally wrong. One of mine did not re-flash correctly, however it was recoverable.

Filter not required for testing purposes.

But a way to plug it in to a standard BT socket is needed - filter is often easiest way to do that but you can get cables and adapters that would do the connector conversion.

True, just trying to rule out a filter issue.

Then how would I connect the modem when the test socket only has a BT socket and the modem has an RJ11 plug?

Edited by deleted (Fri 19-May-17 09:52:18)

As per ian72 post.

Things like this or this were what I was suggesting.

Fair enough point. I think I have a BT to RJ11 lead somewhere but it was easier to put my hand on an old filter (I haven't used one since I started the FTTC trial in 2009).

Does your Huawei HG612 have a black PSU with it? If so these are known to go faulty but as your modem is out of warranty then best to buy your own VDSL modem/router.

Somewhat curious at Uno suggesting a possible £220 bill if Openreach prove the fault to your equipment ....

The usual figure touted around £130 ..... Why so much more ??

In the OP's opening post he states he was an early adopter of FTTC, so he will be using an engineer installed faceplate filter already, this should negate the having to test from the test socket bit except maybe to rule out the filter.

Me, I bet the modem is on its way out.

In reply to a post by Zarjaz:

Somewhat curious at Uno suggesting a possible £220 bill if Openreach prove the fault to your equipment ....

The usual figure touted around £130 ..... Why so much more ??

Broadband Engineer Related Charges: https://www.uno.net.uk/price-list/

Perhaps because it's for a Special Fault Investigation (SFI) visit?
They said the base call out charge is £182+VAT
Any work done to internal wiring: £44+VAT
Any work done to internal equipment: £22+VAT

I have no intention of being charged because of a fault my end, but I worry that I'll eliminate everything and end up in the worst situation; an external cause. In which case, I get charged but the problem isn't fixed and maybe never gets fixed if we can't find the source of the problem!

It does have a black PSU and I've ordered a 'BT refurbished' modem from My Memory with so we'll see what that brings.

That said, the connection has been more stable over the past 24hrs but at less than half my normal speed.

Start with the replacement modem.

Because you already have an SSFP fitted by the installing engineer that negates the possibility of the
Internal wiring modules having to be checked/charged for.

In fact the CP has various options over which modules of the SFI visit they wish the engineer to check. For instance, if they don't state the 'end users equipment' module then the SFI cannot claim to have tested that bit, and Openreach can't Bill the CP for it either.

I'm with you on this my first port of call would be the modem.

Thanks, I'll try it as soon as it arrives. I'll unlock it so I can get more detailed stats, too.

The master socket is an NTE5C with Mk4 SSFP. The only other socket is back wired from the master (by Openreach) but trying the test socket in the master to rule out the extension didn't seem to make any difference as far as I could see.

The connection has been more stable in past 24hrs but speed is way down. Presumably this is DLM kicking in but not sure if that in itself gives any clue as to where the problem might be or not.

I was trying to negate the filter as an issue.

I understand, thanks. I wasn't necessarily worried about the filter as it hasn't been part of my existing setup but it's something I'll bear in mind if other avenues draw a blank.

You might make money on that bet. The 'new' (BT refurb) modem arrived this morning with a brand new white BT branded PSU.

I swapped the modems this afternoon during a bad period of disconnections, and the line hasn't dropped all day since. I'll reserve judgement until I've gone a couple of days without a disconnection, but I'm now reasonably confident that the modem was the culprit.

Only problem now is that DLM has taken my profile down to 30Mb and I'm currently getting 29Mb down and 5Mb up. I wonder how long I can expect it to be before I'm back to full speed and no interleaving?

See my other reply but swapped modem today and looks like it may have been a faulty modem.

Good to know, monitor for a while before making a definitive conclusion.

If only one could make a living out of this some way !

Well please do come back and update either way.

In theory DLM *should* slowly (talking weeks not days) creep back up.

In reply to a post by Gozaradio:

Only problem now is that DLM has taken my profile down to 30Mb and I'm currently getting 29Mb down and 5Mb up. I wonder how long I can expect it to be before I'm back to full speed and no interleaving?

There could be a reaction within a couple of days wrt the first relaxation. Possibly even a second. Full removal could take months, if at all without some Openreach intervention.

As for interleaving, I can't remember if you are on a Huawei or ECI cabinet. If it is Huawei then G.INP should kick in after about two days. Whether or not that improves your connection speed depends of course on what it does with the banding. It does basically remove interleaving, retaining a depths of 8, 12 or 16. (A value of 4 accompanied by an upstream 4 can appear with some modems, but is rare).

Max Attainable will rise a lot and latency fall if it does become active.

Edited by RobertoS (Sun 21-May-17 13:47:49)

Useful information to know, thanks. I'm on a Huawei cabinet.

However, having just checked in after being out for most of the day, I see that there was a disconnection in the past hour due to a NAS-Error (like all the other disconnections). Uptime was 15 hours which is on par with longest uptime I've had in the past 10 days, so more monitoring required but if I still get disconnections, over the next couple of days, I think I'll have to give in and order the SFI.

If it is one disconnection a day that could be DLM as I have found even with a stable line DLM will re-assess every couple of days. Although I now have 6 days uptime.

Now is the time to flash one of the modems ... then sit that on the line with all the stats available.

+1

Thanks. I tried flashing the older one last night but couldn't access the web interface. Will have a go with the other one. Does it matter whether the modem is connected to DSL or not at the time?

I'm also working on the basis that I should use the version ending in 08 because of G.INP - does that seem right?

30SP08

Take the one with telnet and GUI. GUI is unreliable for stats but has a few things easily done that are hard in telnet.

Ok thanks. Will have a go now.

Right, got all that sorted - unlocked the modem, put the children to bed and then set about trying to set up the modem so that I could access it through my router rather than having to stand with a laptop in the hallway.
Couldn't understand why I couldn't access it on LAN despite changing IP to a less likely to be used address until I remembered that Apple routers use 10.0 range by default rather than 192.168... Changed it to 10.0.1.12, made a DHCP reservation by its MAC just in case, and now I can access it from everywhere.

Anyway, I'll set up HG612 stats and report back but these are the current stats if they tell a story:

xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 0
Last initialization procedure status: 0
Max: Upstream rate = 28275 Kbps, Downstream rate = 80448 Kbps
Bearer: 0, Upstream rate = 4999 Kbps, Downstream rate = 29997 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): 21.7 23.4
Attn(dB): 15.2 0.0
Pwr(dBm): 12.2 6.8
VDSL2 framing
Bearer 0
MSGc: -6 -6
B: 130 32
M: 1 1
T: 0 0
R: 16 10
S: 0.1381 0.2072
L: 8513 1660
D: 4 4
I: 147 43
N: 147 43
Q: 4 4
V: 2 0
RxQueue: 128 85
TxQueue: 32 17
G.INP Framing: 18 18
G.INP lookback: 31 17
RRC bits: 24 24
Bearer 1
MSGc: 90 58
B: 0 0
M: 2 2
T: 2 2
R: 16 16
S: 10.6667 16.0000
L: 24 16
D: 1 1
I: 32 32
N: 32 32
Q: 0 0
V: 0 0
RxQueue: 0 0
TxQueue: 0 0
G.INP Framing: 0 0
G.INP lookback: 0 0
RRC bits: 0 0
Counters
Bearer 0
OHF: 0 0
OHFErr: 0 0
RS: 210410512 3331497
RSCorr: 0 0
RSUnCorr: 0 0
Bearer 1
OHF: 454225 455815
OHFErr: 0 0
RS: 2724981 1823262
RSCorr: 0 0
RSUnCorr: 0 0

Retransmit Counters
rtx_tx: 6484911 0
rtx_c: 0 28004200
rtx_uc: 0 5892937

G.INP Counters
LEFTRS: 0 6751
minEFTR: 29991 4997
errFreeBits: 3334272 87862577

Bearer 0
HEC: 0 0
OCD: 0 0
LCD: 0 0
Total Cells: 420864205 0
Data Cells: 11512545 0
Drop Cells: 0
Bit Errors: 0 0

Bearer 1
HEC: 0 0
OCD: 0 0
LCD: 0 0
Total Cells: 0 0
Data Cells: 0 0
Drop Cells: 0
Bit Errors: 0 0

ES: 0 0
SES: 0 0
UAS: 25 25
AS: 7294

Bearer 0
INP: 52.00 55.00
INPRein: 1.00 1.00
delay: 0 0
PER: 0.00 0.00
OR: 0.01 0.01
AgR: 30227.58 5075.98

Bearer 1
INP: 2.50 4.00
INPRein: 2.50 4.00
delay: 0 0
PER: 16.06 16.06
OR: 47.81 31.87
AgR: 47.81 31.87

Bitswap: 6149/6149 0/0

Total time = 2 hours 1 min 59 sec
FEC: 0 0
CRC: 0 0
ES: 0 0
SES: 0 0
UAS: 25 25
LOS: 0 0
LOF: 0 0
LOM: 0 0
Latest 15 minutes time = 1 min 59 sec
FEC: 0 0
CRC: 0 0
ES: 0 0
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
Previous 15 minutes time = 15 min 0 sec
FEC: 0 0
CRC: 0 0
ES: 0 0
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
Latest 1 day time = 2 hours 1 min 59 sec
FEC: 0 0
CRC: 0 0
ES: 0 0
SES: 0 0
UAS: 25 25
LOS: 0 0
LOF: 0 0
LOM: 0 0
Previous 1 day time = 0 sec
FEC: 0 0
CRC: 0 0
ES: 0 0
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
Since Link time = 2 hours 1 min 33 sec
FEC: 0 0
CRC: 0 0
ES: 0 0
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0

At a quick glance, it's been up just over two hours at the time you took the stats, G.INP is activated, the line is capable of the full 80/20 sync, and you are banded at 30Mbps down, 5Mbps up. You also have the unusual interleave of depth 4/4 on Bearer 0. You have zero additional latency imposed by DLM.

Error rates .... what errors? LOL

(Bearer 0 is the normal channel. Bearer 1 is a dedicated channel for G.INP to use and isn't present if not activated).

Edit: Which HG612 have you flashed?

Edited by RobertoS (Sun 21-May-17 23:10:21)

Thanks for that, RobertoS, much appreciated.

I presume the lack of errors is a good thing! I'm still getting my head round interleaving so in what way is my interleaving depth unusual, and in a good or bad way?

I flashed the 'new' modem, so the 3B model.

(Edit: changed 'router' to 'modem')

Edited by deleted (Sun 21-May-17 23:18:34)

Just unusual. Particularly with an HG612. That's about all I know.

We don't often see it. The first number is the downstream interleaving and the second the upstream.

Fast Path is 1.

With normal interleaving on FTTC the down is usually in the hundreds or thousands. Scary compared to ADSLx but that's how it is. Upstream doesn't seem to go off Fast Path very often at all.

With G.INP, as I said earlier, the most common setting is 8/1. Next most common seems to be 16/1. I think I have seen the occasional 12/1. Half a dozen 4/4, and got that consistently with one of four modems I experimented with before plumping for what I'm using now. By "consistently" I mean I did swap that one in and out a couple of times and it always did it. All the others gave/give 8/1.

Zero errors suggests that it won't be long before the banding is relaxed. Though as has been said it could be many weeks before it is completely removed. If it is!

Thanks again for the insight. Hopefully the old modem was dying and I'll be back to normal in a few weeks - frustrating as it is to not be at full speed, I'll take 30/5 over a constantly interrupted connection any day of the week, especially when I'm trying to work!

Leave it and the router on permanently for now if you don't normally.

Well, I hope I'm not speaking too soon but it looks like the modem was the culprit; modem has been up for 4 days 3hrs at the time of writing. I've left HG612 stats running the whole time but I don't think it's gathering ongoing stats. I haven't had a chance to investigate but snapshot stats seem to be working.

Anyway, I'll consider the problem solved if it stays up long enough for the profile to start returning to normal.

To get ongoing stats you need to have DSLStats installed and running.