ADSL2+ and now VDSL disconnections

My dad has been having a problem for months whereby the connection is lost randomly between the hours of 11 and 3pm, it can be once, it can be several times in a row.

He has upgraded to fibre in an effort to resolve the issue because the SFI engineers has exhausted their tests.

This also hasn't solved it, however, what is interesting is that 4 different routers, have all rebooted and lost connection, rather than just simply dropping the connection, this consisted of 2x BT Home HUB 2.0a, a Fritz!Box and now a Plusnet Hub One.

Is there any way that something down the phoneline could cause the router to reboot? Or is this looking more like a power problem?

The Home Hubs (which the PlusNet is too) have a tendency on resyncs to drop everything and appear to reboot.

Not sure on the Fritzbox...

Trying a Huawei HG612 that is unlocked as a bridge to one of the home hubs or something like the TP Link W9970 (http://amzn.to/2kasjhK £37 on Amazon) which can run in modem or router modes may be more beneficial in terms of figuring out the issue.

If the disconnects are without fail between 11am and 3pm it points to a massive noise spike generated by something electrical nearby.

I have a ECI modem which I no longer use, but Dad's on a Huawei cab, will that do for testing?

If it's locked then it's less use that the Hub One, which at least gives you some statistics. You can use the RouterstatsHub 5A to monitor the stats on the Hub One.

If might, but you'd have no access to stats, ideally you want a Broadcom chipset in the modem you use. The one I linked to, or the HG612 does.

My first guesses would be that something generates spikes of noise in that timeframe, or you have a form of developing, intermittent high-resistance fault. Perhaps triggered as the day warms up.

My parents suffered the first kind of problem from 430pm through to 9pm. Fixed by a proper filtered faceplate, and removal of the ring wire.

I had the second issue on one line, which thankfully did disappear after upgrading to fibre.

The first step I'd take would be to get some monitoring software running with a modem that allows the data to be read. Graphing the SNRM will help show these; adding the error rates will help too.

Intermittent faults are a pain to diagnose. Graphs can help...

I have been having this problem for quite sometime and as yet have not found a pattern. This has happened whilst I was on ADSL and continue though to VDSL .ADSL was Talktalk which took them 2-3 months to apparently fix it. Changed to VDSL a few months later from PlusNet to see the problem raise it`s self again.

Had a lot of engineers out several things done to the copper connection but has still not corrected the fault. The fault rectifies its self after several retrains sometime returning to ADSL speeds needing further retrains to get back to VDSL speed. The fault is totally intermittent the connection can run fine for up to a month or more. Also suffer with packet lose and sometimes bad single channel streaming. causing stuttering or buffering of video.

I have finally got an appointment for a SFI to attend after get a more helpful ear but it took a near heated discussion with a front line customer advisor and Manager and a posting on the community forum to make this happen. I am thinking a Openreach/ISP fault at the exchange or in the network. Hoping the SFI actually pin points the fault but my confidence is low.

What I was suggesting is the monitoring of line stats 24*7 to see if the graph shows some sort of pattern

And it may be the network is perfectly fine, but some local garage that does arc welding at those times of days is causing a big RF burst knocking out yours and maybe other lines.

Chasing down this issues is not simple or quick to do.

In the late evening. I would be surprised. Any I live quite rural the nearest garage is at 1/2 mile away or more away. There a double glazing company near by but they do not work after 18:00. The problem occur even during their shut down between Christmas and New Year.

What a RF burst does not explain is why does the connection does not come back at VDSL rates but ADSL speeds. The DLM on VDSL is meant to be switched off after the first 10 Days. so it should not be a line management issue. It does not explain the phone problems, packet loss or poor single channel downloads at any time, morning, afternoon and night.

In reply to a post by retracor:

The DLM on VDSL is meant to be switched off after the first 10 Days.

No, DLM is turned off for the first 2 days and then it's switched on.

Not even that . (My bold and underline):-

2.2.1 Dynamic Line Management
Dynamic Line Management (DLM) is employed in GEA-FTTC. DLM constantly manages lines to maintain a target link quality (speed and stability). It does this for as long as the product exists.

At provision, the line is put on �wide open� VDSL2 line profiles allowing the upstream and downstream line speeds to run at the upper limit of the product option selected.

On the first day of operation, DLM will intervene if severe instability is detected. Otherwise, DLM will wait until the day after provision before deciding if it must intervene, provided that the line has been trained up for at least 15 minutes during the preceding day.

Which in practice means it will leave it alone, or during the night at the end of the second day, when it may add interleaving, and/or G.INP, and/or in serious cases Banding. Changing its mind perhaps at some time in the future.

Edited by RobertoS (Sat 21-Jan-17 15:29:41)

The garage was just an example, many things can create RF that kills ADSL/VDSL2

As for not explaining the ADSL speed issue, actually it could, i.e. noise may follow a pattern (and that's the clue if you find a pattern to drop-outs that its from a source, rather than a wiring fault) of high burst followed by a smaller burst that is not so bad and modem will resync to some extent (this scenario is why banding exists)

The 10-day period is a BT Wholesale myth, despite them continuing to go on about it. Particularly in relation to fibre connections.

See this page for more about it on BT Wholesale ADSLx. On Openreach FTTC the main thing it does is set the IP Profile, instantaneously on every change of connection speed. It may also record the lowest sync during the first 10 days as it did on ADSLx, but that's it.

As William said, correctly in a way but dodgy in the detail, DLM is likely to do nothing for the first two days. He was wrong only in thinking it wasn't running at all and would never do anything in that period.

As BatBoy advised, ideally you should run a diagnostic graphing program 24/7. Of the kit you listed I don't think any allow that except perhaps the Fritz box. Are you on Windows or an Apple machine?

just checked my TP-link router (not PN homehub) and it is showing:

I trust that should put some light on the situation.
Line Status: connected

upload errors of 4294967156
download errors 97

Normal upload speed 1,9 approx. on 40/2 VDSL
current upload approx.0.75
Told by PN the upload should always be 2Mbps.

DSL Modulation Type: VDSL2
Annex Type: Annex A/B/L/M

=================Upstream___Downstream

Current Rate(kbps)_____885______39998
Max Rate(kbps)________897_____ 55142 Max for upload should always be 2000 on 40/2

SNR Margin(dB)-------------10.7------12.6

Line Attenuation(dB)------31.1-------21.7

Errors(pkts)-----------4294967156-----97

Edited by deleted (Sat 21-Jan-17 18:07:23)

You can probably ignore the upstream error figure and just watch for it changing - it is a common bug when a twos complement number is incorrectly displayed ...


Your 4294967156 is very similar to my 4294967290

While similar it is far enough away to suggest a fair few errors and the upload sync so low when getting a full 39998 sync suggests something wrong. Exactly what I don't know.

Probably not the micro filter, as that would also be impacting the downstream, as the bands start Down, Up Down Up Down Up (if brain recalls correctly)

If any HomePlugs in the home or a neighbour who shares an adjoining wall try turning them off and unplugging them (its rare but sometimes people do get issues, since they share a common set of frequencies)

Also does using the test socket make any difference, i.e. no phones connected and none of the extensions are working i.e. proves the test socket is just that and no odd star wiring going on

In reply to a post by MrSaffron:

Probably not the micro filter, as that would also be impacting the downstream, as the bands start Down, Up Down Up Down Up (if brain recalls correctly)

Up0 is te first band up to tone 32 with Down starting at tone 33 ...


from my modem:
Medley Phase (Final) Band Plan
US: (7,32) (871,1205) (1972,2782)
DS: (33,859) (1216,1961) (2793,3970)

Poor brain got it wrong way around then - so raises a chance something in the low frequency band causing problems.

An unfiltered device phone/fax/sky box or failing microfilter can sometimes do this

Thanks to you all for your help and guidance

No power plugs next door I would be surprised if he knew what there were. Not a filter problem as OR already thought that and changed the master socket for a separate modem and telephone type so no filters required on any telephone etc.

the router has lost sync two or three times in the last 12 hours or so needing a reset to sync at the true speed. Had to retype this as it happened during composition of this post.

My neighbour on the other side (not attached to this property) is also on PN but has ADSL.Is it possible that some sort of cross fed would confuse my VDSL and make it try to sync to ADSL.

Cross feed - as in you are sharing the line with a neighbour? Would be readily apparent on the voice side, and unlikely, a source of external RF interference is more likely.

Just to update, since putting the router on a UPS, the line hasn't dropped since.

However, I have noticed that the line rate is just on the cusp of what is considered to be an impacted line.

The engineers did say that the line runs underground from the PCP to the CP with joints outside each property (bridge taps?).

There's no way to replace it either as the cable isn't ducted (so they say).

That could be down to DLM interventions due to the resyncs.

I don't believe so when the downstream noise margin is 6db.

Interleaving and G.INP both retain the 6dB margin. Interleaving on FTTC easily drops the sync speed by 8-11Mps.

Edited by RobertoS (Mon 23-Jan-17 16:17:43)

Bridge tap means a length of wire running off in a third direction, an underground joint would not be a bridge tap.

Rejointing every line outside every property it passes sounds odd too. You probably have a joint outside yours, but only way to know is access to BT line records and even then some stuff is missing

The SFI engineers that have visited the property in regards to the disconnections suggest this is the case, they explicitly stated that there is no way to get the D-side cable renewed or that there is any spare capacity.

Edited by deleted (Mon 23-Jan-17 16:38:34)