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Author Topic: Router dropped uplink power ADSL2+ Fixed, hopefully possible REIN  (Read 1040 times)

aimdev

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Router dropped uplink power ADSL2+ Fixed, hopefully possible REIN
« on: September 09, 2018, 06:51:38 PM »

Hi
For at least a year, my router has been outputting 12dB of uplink power, then suddenly in the early hours it dropped to 10dB, then 7dB.
The attainable speed dropped by 1Mbs from 17.5Mbs
A fortnight later OpenReach turned up to correct a fault, and I got talking to the linesman.
Apparently there was a fault with the connection between the underground junction box and the property of a neighbour about
100m away.
I checked my stats while they were investigating, and the attainable rate jumped up by about 1Mbs and the SNR increased by approx 1dB.
They couldn't find a fault, despite doing a REIN test, so they changed the cable.
My stats have now dropped to 16Mbs, SNR about 4dB (before it was 3dB because I tweaked it to improve the speed)
Errors on ul, low, dl high.


Another neighbour who is on fttc, used to get 21Mbs, has dropped to 16Mbs approx, hovering around the hand-back speed for the cabinet.

The line from the properties to the exchange, approx 1.4km, is all underground.

My question is, have they actually fixed the fault (I have not been in contact with the neighbour yet to see if it is fixed, but the absence of OR vans, I assume it may have)

Any Ideas?

Thanks

Aimee
« Last Edit: September 11, 2018, 03:57:35 PM by aimdev »
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re0

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Re: Router dropped uplink power ADSL2+
« Reply #1 on: September 10, 2018, 01:51:05 AM »

Welcome to the kitz forum!

Based on your wording, is it safe to assume that you didn't raise a fault with your provider? If it is true you did not, then perhaps it was a neighbour?

They couldn't find a fault, despite doing a REIN test, so they changed the cable.
Changed the cable or just just your and/or your neighbour's pair? It seems fairly more plausible for them to have just changed a pair as many are carried in a single "cable". Though I do not know why they would have changed your pair if you had not reported an actual fault with your telecoms provider so there's a possibility that they only fixed a fault on a neighbour's connection if it existed.

Did your modem lose sync with the DSLAM when the work was being carried out? If it did, then perhaps they could have changed something on your line.

My stats have now dropped to 16Mbs, SNR about 4dB (before it was 3dB because I tweaked it to improve the speed)
Errors on ul, low, dl high.
Tweaking the SNRM is not always a wise idea as, while it can yield more bits, it will lead to an increased error rate due to the increase susceptibility to interference - both burst and normal background. Perhaps this is why the errors on the DL are "high".

My question is, have they actually fixed the fault (I have not been in contact with the neighbour yet to see if it is fixed, but the absence of OR vans, I assume it may have)
It's all up in the air at the moment since it is not clear whether you reported it or not, whether or not they carried out any work on your line and whether you were/are actually experiencing symptoms of REIN. Nobody from here will be able to answer that.

Perhaps you could fill us in on what sort of hardware you are using in terms of your modem? And maybe you could also supply some statistics from your modem from before and after/during the problem you experience/are experiencing?

Regards,
re0
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aimdev

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Re: Router dropped uplink power ADSL2+
« Reply #2 on: September 10, 2018, 03:13:58 AM »

Hi
No fault was reported by me as my ISP wont do anything unless the speed drops < 4Mbs and in this case the speed was only down by 1Mbs (dl) 200kbs (ul).
I believe, as they were carry a drum of black cable, the whole cable was replaced. the distance from the junction to the house is approx 10m.
The OR guy did say he may change the cable, not able to confirm.
No disconnection occurred while they were fixing the neighbours problem, just the 1Mbs increase while the neighbours line was disconnected.
OR was at a loss to understand what the fault was.
The line has been stable at 17Mbs, 12dB power, 3dB SNR for at least six months.
The attenuation is 29/30 dB, and the OR guy confirmed that, also the neighbours line tested at 19Mbs, when his cable from the junction box to the house was
disconnected, ie junction to exchange.
The Upload speed change was sudden not gradual, the Rate Attainable, and hence the Download speed was gradual.
The modem/router is a Draytek Vigor 2860, I send snmp data to a database and onto a graph.
The stats collected are
Rate Attainable
SNR
Attenuation
Line Speeds (ul/dl)
Uplink Power

Other statistics are not stored as the 2860 only sends a reduced set of snmp data.
The only recordable change was the gradual drop in Rate Attainable, after a sudden drop in uplink speed and output power.
The down link SNR varies from 3dB to 6dB.

I am curios as to what would cause this when the neighbours line is disconnected the Rate Attainable increases (his house is
about 50m away from me and 50m closer to the exchange).

I am still getting a fair service, but I am considering going to fttc with a different provider when the contract ends
which will give me 16Mbs guaranteed, estimated 21-26 Mbs (DSLAM is about 200m from the exchange, line distance is approx 1400m)
Reset the SNR to 6dB, Power out now 10dB, Rate Attainable 15.5Mbs, will watch it to see if it drops.
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aimdev

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Re: Router dropped uplink power ADSL2+
« Reply #3 on: September 10, 2018, 08:24:43 AM »

Since the reset this morning, here are the stats after 5 hours of use.

Any comments would be really helpful.

Thanks

Aimee

> adsl status

  --------------------------- ATU-R Info (hw: annex A, f/w: annex A) -----------
   Running Mode            : ADSL2+ Annex A       State                : SHOWTIME
   DS Actual Rate          : 15358000 bps   US Actual Rate       :   799000 bps
   DS Attainable Rate      : 15556000 bps   US Attainable Rate   :   945000 bps
   DS Path Mode            :  Interleave    US Path Mode         :  Interleave
   DS Interleave Depth     :      352       US Interleave Depth  :        8
   NE Current Attenuation  :       29 dB    Cur SNR Margin       :        6  dB
   DS actual PSD           :    18. 7 dB    US actual PSD        :    10. 0  dB
   NE Rcvd Cells           :  3755701       NE Xmitted Cells     :   570352
   NE CRC Count            :    18717       FE CRC Count         :       40
   NE ES Count             :    10109       FE  ES Count         :        8
   Xdsl Reset Times        :        0       Xdsl Link  Times     :        3
   ITU Version[0]          : 00000000       ITU Version[1]       : 00000000
   ADSL Firmware Version   : 05-07-01-08-00-01
   Power Management Mode   : DSL_G997_PMS_L0
   Test Mode               : DISABLE
  -------------------------------- ATU-C Info ---------------------------------
   Far Current Attenuation :       14 dB    Far SNR Margin       :       15  dB
   CO ITU Version[0]       : b5004244       CO ITU Version[1]    : 434da3f7
   DSLAM CHIPSET VENDOR    : < BDCM >
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re0

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Re: Router dropped uplink power ADSL2+
« Reply #4 on: September 10, 2018, 07:38:18 PM »

No fault was reported by me as my ISP wont do anything unless the speed drops < 4Mbs and in this case the speed was only down by 1Mbs (dl) 200kbs (ul).
Indeed. The speed is variance is certainly insignificant for an ISP to bother OR. Perhaps if stability had been impacted to a degree which could be considered degraded then perhaps they would be more inclined to investigate.

I believe, as they were carry a drum of black cable, the whole cable was replaced. the distance from the junction to the house is approx 10m.
The OR guy did say he may change the cable, not able to confirm.
Then they have not touched your connection. You are still on the same cable and pair based on what you have mentioned.

No disconnection occurred while they were fixing the neighbours problem, just the 1Mbs increase while the neighbours line was disconnected.
. . .
I am curios as to what would cause this when the neighbours line is disconnected the Rate Attainable increases (his house is
about 50m away from me and 50m closer to the exchange).
ADSLx and VDSLx co-exist in the same spectrum, though if memory serves VDSLx has PSD masking to reduce the impact on ADSLx technologies. I am not sure how much impact your neighbour's FTTC would have on your ADSL connection (I imagine it should only have a little impact depending on the effectiveness of PSD masks and harmonics). It seems fairly probable that there is some interference somewhere caused by the neighbour's line operating, but I cannot be sure of what exactly.

I am perhaps thinking that the problem could be REIN. Perhaps your neighbour is using a modem that is not SIN 498 compliant and is generating interference. Just because a modem is not certified compliant with the SIN 498 does not mean it will create issues, but some modems using the dreaded MediaTek chipset (some ASUS devices I know for sure) have options that should not be adjustable from the End User; notably UPBO which should never be disabled as it is capable of causing disruption to other lines.

I have made what I believe to be an educated guess, but perhaps some others on the forum could share their ideas?
« Last Edit: September 10, 2018, 07:42:06 PM by re0 »
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aimdev

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Re: Router dropped uplink power ADSL2+
« Reply #5 on: September 10, 2018, 09:35:22 PM »

Hi
Just a clarification, the property with the 'bad' cable is on adsl2+, he suffered quite a large loss, 19Mbs down to 11 dB apparently., the other neighbour is on vdsl, they had a drop to close to 16Mbs from 22Mbs
No work was done on my line, I got all the info by chatting to the OR guy, and mentioning that I had suffered a slight degradation, which disappears when he disconnected the neighbours line, done to assist him for the good of all.

On my system I set the snr to 6dB. as stated in the previous message, been stable. Early this evening I put a couple of ferrites on the phone line, rebooted modem as the snr went below zero.
When it came back, snr was 4, speed increased from 15.55Mbs to 16.47Mbs, on the attainable rate, power out on the ul 7dB.
REIN may be an issue, the OR man was going to use his transistor radio to see if it was an issue, however he left before I could talk to him.
Re the modem type, don't think he would use anything other than supplied, but when I see him I will ask.
Any ideas what frequency and modulation type I should set up to see if there is localised interference?
« Last Edit: September 10, 2018, 09:39:05 PM by aimdev »
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aimdev

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Re: Router dropped uplink power ADSL2+
« Reply #6 on: September 11, 2018, 03:56:44 PM »

Looks like it may have been a REIN issue, attainable rate  (dl) improved, error rates dropped ul speed still a bit low, output power 7dB
The neighbours speed has increased, hopefully everybody's broadband will improve when the dlm and dslam gets itself sorted.
I wonder if if the power supply cable to the property was too close to the phone line, when the houses were constructed, broadband was not even available.
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re0

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Re: Router dropped uplink power ADSL2+ Fixed, hopefully possible REIN
« Reply #7 on: September 14, 2018, 11:20:14 PM »

Sorry that I have not really been able to add much to this since it is not something that I have experienced myself and I am not sure if I can provide any further insight. Without knowing exactly what the engineer has done it is only going to be educated guesses, and I don't think I have any right now. :(

Hopefully the problem has been resolved though. By all means update this topic if you still have issues.
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aimdev

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Re: Router dropped uplink power ADSL2+ Fixed, hopefully possible REIN
« Reply #8 on: September 15, 2018, 07:13:36 AM »

Sorry that I have not really been able to add much to this since it is not something that I have experienced myself and
I am not sure if I can provide any further insight. Without knowing exactly what the engineer has done it is only going to be educated guesses,
and I don't think I have any right now. :(

Hopefully the problem has been resolved though. By all means update this topic if you still have issues.
No Worries, any comments/ideas are welcome.
The Attainable rate has increased to just under 19Mbs, this happened the day after the REIN test and the discovery of the interference source.
On that day there was an OR van around, not sure what they did.
The actual connection speeds have not increase to their original values, but
a. the isp wont do a dlm reset if that is what is required (that was their response last time, but a gentle kick sorted it), and
b. they are shortly being dispensed with as I am transferring to a new isp's fttc service.

The REIN page on this site was helpfully, got the old tranny radio out and went hunting!!

One mystery is the attenuation of the down link, typically 29dB, which equates to approx 1.8km, but if the route I was given is correct, the distance of 1.4km equates to about 20dB.
The alternative routes are about the same.
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re0

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Re: Router dropped uplink power ADSL2+ Fixed, hopefully possible REIN
« Reply #9 on: September 15, 2018, 10:30:26 PM »

Working out a distance from attenuation won't yield precise results since you have to bear in mind that it is measuring the loss of signal which varies depending on actual line characteristics. Different gauges of cabling will have varying losses and therefore without knowing exactly which gauge was used and the distance it travels you will only will have a rough estimate (though if you knew the exact distances of the cabling then it would certainly make the whole excercise redundant :D).

Essentially, your line has a loss which equates to an attenuation of 29 dB but it could actually be closer 1.4 km as it may be using a smaller gauge and therefore subject to a higher loss of signal. Though, as we all know cabling is not always so direct and it may take slight detours here and there.

Funnily enough, I was given a similar length figure from an engineer for my D-side and E-side cable combined though it performed more like it was 2x the distance. Even more funny is that the TalkTalk wholesale checker believes that on ADSLx the line would be pretty much 2x as fast as what the BT wholesale checker says, so I do wonder if the distance is correct but smaller gauges and aluminium have basically almost halved the speeds of what had otherwise been possible on a larger gauge.
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aimdev

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Re: Router dropped uplink power ADSL2+ Fixed, hopefully possible REIN
« Reply #10 on: September 15, 2018, 10:45:23 PM »

Working out a distance from attenuation won't yield precise results since you have to bear in mind that it is measuring the loss of signal which varies depending on actual line characteristics. Different gauges of cabling will have varying losses and therefore without knowing exactly which gauge was used and the distance it travels you will only will have a rough estimate (though if you knew the exact distances of the cabling then it would certainly make the whole excercise redundant :D).

Essentially, your line has a loss which equates to an attenuation of 29 dB but it could actually be closer 1.4 km as it may be using a smaller gauge and therefore subject to a higher loss of signal. Though, as we all know cabling is not always so direct and it may take slight detours here and there.

Funnily enough, I was given a similar length figure from an engineer for my D-side and E-side cable combined though it performed more like it was 2x the distance. Even more funny is that the TalkTalk wholesale checker believes that on ADSLx the line would be pretty much 2x as fast as what the BT wholesale checker says, so I do wonder if the distance is correct but smaller gauges and aluminium have basically almost halved the speeds of what had otherwise been possible on a larger gauge.

Hi
Having had quite a few chats to the OR wiremen, the following pearls of wisdom were supplied...
The cable is not aluminium
The cable is a multiple twisted pair which goes directly to the PCP, feeding around 25 properties.
The cable was installed about 20 years ago.
The distance was worked out on a cycling mapping application where you can follow the actual road faithfully, ie not
just 'crow flies' estimates (I have never ever seen a crow fly in a straight line, they are always all over the place!!)
The attenuation varies, 27dB on the optimistic isp router, 29dB on the pessimistic Vigor 2860.
Mystery, will have to see what its like when the hybrid fibre is connected.
Thanks for your comments.
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re0

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Re: Router dropped uplink power ADSL2+ Fixed, hopefully possible REIN
« Reply #11 on: September 16, 2018, 12:13:00 AM »

It's not unusual for different modems to give different attenuation values for the same line. This is down to the combination of different chipsets and modem design, and even "identical" modems (same make and model) could give you a slightly different reported value due to manufacturing variances/inconsistencies. The modulation in use will also make a difference to the reported attenuation; ADSL2+ will typically give an attenuation increase of ~3 dB over ADSL1/ADSL2 due to doubling of the frequency band (2.2 MHz vs 1.1 MHz), though this is not important here because you're only using ADSL2+.

Mystery, will have to see what its like when the hybrid fibre is connected.
If you meant in terms of speed, I think you already have a vauge idea of what to expect. :) As per a previous post of yours:
I am still getting a fair service, but I am considering going to fttc with a different provider when the contract ends
which will give me 16Mbs guaranteed, estimated 21-26 Mbs (DSLAM is about 200m from the exchange, line distance is approx 1400m)
Seeing as you also mentioned your neighbour getting 21 Mbps then I would probably expect roughly the same figure. https://www.dslchecker.bt.com (if you haven't already used it) tends to give very accurate figures of what to expect.

Not that I want to complicate the matter for you, but I have noticed that the Vigor 2860 uses a Lantiq chipset. Not that it will cause issues, but I have personally experienced issues with Lantiq even on a very short FTTC (VDSL) line with disconnections and high error rates leading to DLM taking action and punishing the connection for a long time. I had to switch it out for a modem with a Broadcom chipset before it started recovering. Granted, it was a variant of the Home Hub 5A (Plusnet Hub One in specific) and may have been an earlier and more problematic chipset/firmware version, but I have continued to read reports of newer hardware using Lantiq (even the Vigor 130) having disconnections and general stability issues. Don't worry about it now, but perhaps be aware of it if you experience issues.
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aimdev

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Re: Router dropped uplink power ADSL2+ Fixed, hopefully possible REIN
« Reply #12 on: September 16, 2018, 06:45:45 AM »

Thanks for the warning. I am also getting the ISP modem, which is also Plusnet Hub One , how spooky. I can piggy back the ISP modem as WAN2 on the vigor, but I will loose the snmp feed to my graphing system. :(
Do you have any recommendations for a decent snmp capable vdsl modem using broadcom chips in the event the Vigo plays up? The vigor switch also has a tee function so I can monitor the traffic.
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re0

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Re: Router dropped uplink power ADSL2+ Fixed, hopefully possible REIN
« Reply #13 on: September 16, 2018, 05:16:54 PM »

I do not want to make any recommendations since I am not aware of all your requirements. Your best bet is to look around and possibly create a topic in Broadband Hardware (https://forum.kitz.co.uk/index.php/board,5.0.html) with your requirements since there are going to be people with similar setups to you.

If you're looking for combined modem-router devices then https://forum.kitz.co.uk/index.php/topic,14436.0.html and https://www.ispreview.co.uk/index.php/2018/06/2018-update-best-vdsl-routers-for-uk-fttc-fibre-broadband-isps.html may be a good place to start.

I typically opt for Billion devices, though I cannot currently recommend the 8800 AXL R2 (which has SNMP) because there is currently a very annoying issue with rebooting that I am awaiting information from support about. It may be a hardware fault with my unit, but it could also be a firmware issue.

The general consensus abridged:
  • Absolutely avoid devices with MediaTek at all cost (typically in very cheap hardware and even some ASUS devices).
  • Devices with Lantiq may be OK but have been known to be problematic.
  • Most Broadcom chipset devices are safe, though I am under the impression BCM 63168 is preferable to BCM 63381.
While not absolutely necessary, purchasing a device which has passed the MCT (an up-to-date list is available at https://kitz.co.uk/routers/MCT.htm, March 2018) ensures the device you are purchasing is compatible with Openreach DSLAM hardware. Though there are a lot of devices absent from that list that work fine.

The thing is, the Vigor may be just fine. It's an expensive piece of kit so I wouldn't replace it lightheartedly. You should definitely give it a go first and ensure you are using recommended firmware.

Some other handy resources:
https://wiki.kitz.co.uk/index.php/BCM_routers - A sizeable list of devices with Broadcom chipsets.
https://wikidevi.com/wiki/Main_Page - A wiki with a lot of modem/router hardware listed.
https://openwrt.org/ - OpenWrt wiki contains information regarding chipsets.
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aimdev

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Re: Router dropped uplink power ADSL2+ Fixed, hopefully possible REIN
« Reply #14 on: September 16, 2018, 05:24:37 PM »

Thanks for the reply.
I went onto the Vigor board, it appears there are a number of issues with the 130 and the 2862.
I will use the Plusnet modem initially then try out the Vigor to see if its ok.
 
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