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Sync dropping, everything else perfect

Anyone have a clue what might be happening when I have regular (every day or couple of days) resyncs when the download throughput drops by another 2Mpbs. Usually around the 4-6am window when I believe BT do their firmware changes. It was 40Mbps to start with and over this month has dropped to 28Mbps. Hasn't affected my use yet but it will if it carries on losing at the same rate for the rest of the month and I'll be down to ADSL speeds. Quiet Line Test on a corded phone is excellent and clear.

TBBQM show nothing untoward with all pings pretty well as the minimum 8ms latency, and no packet loss. The router stats (Fritz!) all appear in order with no errors recorded over 24 hours. INP though is 44, stable Noise Margin at 12/13db, and attenuation 24 (though changed from 37, not sure why that's happened - I thought it was related to distance from the cab?).

Blame the modem (but it's working ok in all respects) or the DLM, presumably they're not talking to each other right, though not sure what I can do about that - can a customer get it reset? Or is there something that wouldn't evidence on the line stats?
 
The answer to my question is obviously . . . nothing, then. Nothing new there. The broadband publicity machine is about faster. Anything not in the politically-correct script drops off the radar.
 
Sadly I believe that a DLM profile reset requires an engineer visit to the cabinet on FTTC lines, which can attract a cost if no fault is found.

Clearly something is wrong as otherwise your line wouldn't need to resync and lose speed so much, although some clues should be showing in your stats.

Do you have a fuller copy and paste of your stats and do those stats also give you a reading for your Max as well as Current Rate (Mbps)? Also you give attenuation for downstream, but not upstream?

Did the speed loss start after your attenuation reading change from 24 to 37 and how long ago was that?

Remember that any significant loss of speed is something that you can raise with your ISP as a fault and the more evidence you make of the drop the more that will help your case.
 
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I would be looking at 3rd party issues.

Has anything changed near your property in the last month or so (between you and the cabinet)

Is there any type of factory nearby, could they have new machinery being used at those times.

I had issues for many years with equipment at the factory opposite my house causing wideband RF noise, covering MW radio right up through the 2.4GHz bands. With OFCOM charging ~£150 PER HOUR to investigate RF issues, only the big boys can get them involved in investigating.
 
Nothing changed locally. It's a rural residential estate.

Full Fritz stats:
Negotiated Connection Properties
Receive Direction Send Direction
Max. DSLAM throughput kbit/s 27400 6000
Min. DSLAM throughput kbit/s 128 128
Attainable throughput kbit/s 42697 6615
Current throughput kbit/s 27400 6000
Seamless rate adaptation off off

Latency fast fast
Impulse Noise Protection (INP) 44 0
G.INP on off

Signal-to-noise ratio dB 13 6
Bitswap on off
Line attenuation dB 22 24

Profile 17a
G.Vector off off

Carrier record A43 A43

Error Counter
Seconds With Not Remediable Errors (CRC)
Errors (ES) Many
Errors (SES) per
Minute Last
15 Minutes
FRITZ!Box 0 0 0 0
Central exchange 1 0 0.04 0

Now this is interesting. Resyncs happen several hours, or days, after massive errors (hundreds per minute) occur, starting usually in the 4am to 6am window and continuing until the resynch when they clear for hours or days; or vice versa. As this morning, though no resync. At all other times the error rate is zero.

The stats above were taken after I used the router's option to roll back the router's DSL firmware. They haven't changed EXCEPT that the attainable download has risen from the same as the throughput to the usual 42 Mbps. The new firmware was installed before Christmas. The speed drops and errors did not start before March.

The attenuation dropped from 37 to 24 when the throughput dropped from 32Mbps to 27/6 in the last drop, at the same time as SNR rose from its historic 9db (consistent) to 12/13.

I know these questions are unanswerable state secrets but:
1. Does DLM do something at around 4 am each morning?
2. Could BT do something with the DSLAM firmware randomly that renders it incompatible with modem firmware with which it was previously working? We could all find ourselves stuffed from time to time presumably?
3. Errors can arise presumably which are nothing to do with the line conditions, but because the two sets of firmware at either end have a falling out, randomly. Like a marriage.

I suppose the only thing I can do is pray that DLM now notices something has changed and responds accordingly; or equally unlikely that AVM (the manufacturer) can eventually find out and alter their firmware as I've sent them the before and after data from the modem using their facility. OpenReach will just do as they please and everyone else has to work around them. Thanks, Ofcom. I thought AVM and BT did speak to each other, but presumably the "independent" OpenReach won't be bound by BT's "anti-competitive" protocols!
 
Last edited:
Above post: here is the TBBQM this morning:
My Broadband Ping

The yesterday /overnight: no errors, everything peaceful with low throughput.
The sudden 4am error mountain et seq
My 10am forced resynch when I rolled back the modem DSL firmware using the Fritz! option. (Though from Dec-March the latest firmware was OK with no material errors, no resyncs, in fact best ever).
Afterwards, everything peaceful again with same low throughput . . . for how long???
 
1. I believe that the DLM batch-processing for line profiles occurs at around midnight every day, so not sure if that's related but 4am seems to be a bit past the window (unless the timings have changed).

2. It's possible for incompatibilities between modem firmware/chipset and Openreach kit to occur, which has happened a few times where ECI related FTTC street cabinets are concerned. This is why BT tends to adopt an approved router programme for their network.

3. Not sure.

Clearly something odd is happening from 4am onwards, which could I suppose be due to a leaky (EMI) AC adapter for something or boiler causing interference either in your house or from a neighbour. Maybe something timed.

In terms of your stats, the upstream figures (SNR in particular) look a little too low for that line and this may be partly connected to where all those errors are coming from. Do you have another VDSL2 router you can test with?
 
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Something to also think about is have you the latest BT approved firmware on your VDSL router?

My sync had a spate of dropping I was using a VDSL router at the time not on the BT approved list, apparently the router manufacturer had to do a lot of extra work on the firmware to get it past BT's stringent tests. So for me there are two firmwares one BT approved and one not approved. I plan to change to the approved one soon to see if it brings things back up.


SNR is another on my router SNR was always around 5-6dB with last drop in sync I noticed downstream SNR now shows 15dB also IPprofile now shows banded to 56Mbps. Yet all tests still show no fault on BT's network making it hard to get back to my 79Mbps or anywhere nearer. To be fair this is not the fault of my ISP as they cannot fix a fault BT's system is set to ignore.
 
I originally thought that about the upstream, but it's been the same for 6 years, with no error issues before March 2017.No one has changed boilers, and we're all retired so 4am timers is too early for us!!! Nothing else electrical on in the vicinity of the router at that time.

There is one other TBB forum user in another part of the country who has a near identical issue including the 4am errors and the one third speed drop, running a Fritz!7490. He's had a DLM reset and new NTE socket. His ISP, Plusnet, seem rather more on the ball than mine, IDNet, who seem to have been a chocolate teapot in this case! But it happens with all of them. We are both now trying the DSL firmware rollback offered by the Fritz; before I go trying the OR modem and IDNet Netgear, or the previous Fritz 7390 (which now seems sorted after it's earlier upload issues a couple of years back). No more speed falls, almost zero errors and no reboots over the last 24 hours at least.

It seems that a few other people are having similar recent symptoms with other modems and at other times, cured by a reboot in most cases. None of us have any clue what is causing it. The randomness seems to rule out the obvious culprits. Maybe Kitz is on the right lines. I thought Fritz! worked with BT, they are normally careful when issuing firmware, it certainly always takes a long time but it's "international" firmware so it has a lot to do. Perhaps that's why they introduced the rollback facility as an alternative. I've yet to hear from them, but that's probably what they'll say. I doubt their firmware is "approved" though, so I'm beyond that one! The first world problems of being an anarchist!
 
OK, I am going the blame BREXIT; everyone wants the foreigners out, and "Fritz" is an obvious German name.

Seriously though, I hope you find a solution.
 
Yep. Decided I can bear a change of ISP for AAISP, which I've been thinking about. Can't really justify IDNet's Fibre Pro on my line and for my usage, and Home1 has a better download cap with more headroom that IDNet's basic package for around the same cost.

Disappointed as IDNet have been really good. I've been spoilt. Still suspect I'm stuck, but I'll know for sure. I'm sure Sky or Plusnet would have been fine, and cheaper (or perhaps EE with the extra phone allowance, I used them as Orange before VDSL, and they were fine too); but as a native anarchist, I can't bear the bureaucracy. I'll have six months to sort the phone line out or reconcile myself to the inevitable, perhaps.
 
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