Kitz Forum
Broadband Related => FTTC and FTTP Issues => Topic started by: xlr8r on June 14, 2021, 11:00:47 AM
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[Moderator note: This topic has been split off from the What's my expected SNR Margin for BT (https://forum.kitz.co.uk/index.php/topic,23768.0.html) thread.]
spotted this topic and wanted to know if anyone can advise on a solution for a similar problem i have with BT VDSL.
I use a Zyxel router (in bridged mode) for modem. and an Asus GT-AX11000 router. Im on FTTC and Cabinet is a Huawei i believe having looked it up)
Every day my line will drop for no apparent reason on the Zyxel (also happens with BT Openreach modem)
Also, Each day my DOWN SNR sits stable (at 5.5) until around 8:30 am when it jumps up to 9.2 ?? it does this every day, and reduces again around 9pm to normal. (see screenshot)
what could cause such a sudden SNR increase ? Ad what could be causing my dropouts ? (let me know if you need any additional data for diagnosis)
thanks
====================================================================================
VDSL Training Status: Showtime
Mode: VDSL2 Annex B
VDSL Profile: Profile 17a
G.Vector: Enable
Traffic Type: PTM Mode
Link Uptime: 0 day: 12 hours: 48 minutes
====================================================================================
VDSL Port Details Upstream Downstream
Line Rate: 11.368 Mbps 59.806 Mbps
Actual Net Data Rate: 11.338 Mbps 59.807 Mbps
Trellis Coding: ON ON
SNR Margin: 6.2 dB 9.3 dB
Actual Delay: 0 ms 0 ms
Transmit Power: 6.6 dBm 13.8 dBm
Receive Power: 0.0 dBm -6.3 dBm
Actual INP: 0.0 symbols 55.0 symbols
Total Attenuation: 0.0 dB 20.7 dB
Attainable Net Data Rate: 11.338 Mbps 70.380 Mbps
====================================================================================
VDSL Band Status U0 U1 U2 U3 U4 D1 D2 D3
Line Attenuation(dB): N/A 29.9 48.6 N/A N/A 15.3 38.4 62.2
Signal Attenuation(dB): N/A 29.0 47.3 N/A N/A 18.0 38.0 62.4
SNR Margin(dB): N/A 6.2 6.2 N/A N/A 9.4 9.3 9.3
TX Power(dBm): N/A -13.0 6.6 N/A N/A 11.6 7.9 5.3
====================================================================================
VDSL Counters
Downstream Upstream
Since Link time = 48 min 51 sec
FEC: 47929003 68
CRC: 65 4
ES: 1 4
SES: 1 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
Latest 15 minutes time = 14 min 51 sec
FEC: 229043 1
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: 265174 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 = 14 hours 29 min 51 sec
FEC: 53381868 79
CRC: 3126 8
ES: 48 8
SES: 48 0
UAS: 1740 1693
LOS: 1 0
LOF: 3 0
LOM: 34 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
Total time = 14 hours 29 min 51 sec
FEC: 53381868 79
CRC: 3126 8
ES: 48 8
SES: 48 0
UAS: 1740 1693
LOS: 1 0
LOF: 3 0
LOM: 34 0
====================================================================================
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...
Every day my line will drop for no apparent reason on the Zyxel (also happens with BT Openreach modem)
Also, Each day my DOWN SNR sits stable (at 5.5) until around 8:30 am when it jumps up to 9.2 ?? it does this every day, and reduces again around 9pm to normal. (see screenshot)
what could cause such a sudden SNR increase ? Ad what could be causing my dropouts ? (let me know if you need any additional data for diagnosis)
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This sounds like some kind of electrical interference occurring only overnight - a faulty streetlight perhaps? Does the line drop coincide with the change of SNRM as your stats are puzzling, showing the circuit being unavailable for nearly 30 minutes (based on UAS count) in 14.5 hours of uptime. Is it really offline for that long or did you take it down manually?
:)
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This sounds like some kind of electrical interference occurring only overnight - a faulty streetlight perhaps? Does the line drop coincide with the change of SNRM as your stats are puzzling, showing the circuit being unavailable for nearly 30 minutes (based on UAS count) in 14.5 hours of uptime. Is it really offline for that long or did you take it down manually?
:)
hi thanks.
This has been happening for years now. I had thought of the streetlight as being a possible culprit but the times are nowhere close. the SNR drops to normal overnight and jumps up again around 8:30am-ish daily.
ill run dsl stats for a couple of days to get a better graph to indicate full days times affected.
i have had the line unplugged a couple of time over last few days (to swap modems for testing) but i gave it 30 mins each time, so as not to get DLM'd.
will post back when i have a better graph ... thanks
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ok, so here is a days worth of SNR roller-coaster'ing....
anything here make any sense to anyone ?
i have tried to determine if anything in my house goes on and off that similar times, but can find nothing... Im stumped with this SNR behaviour....
(https://i.postimg.cc/D0Ts6m78/SNR-WTF.png)
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Sudden large changes like that are almost certainly due to electrical interference. The offending device may not be in your house of course, but the only way to prove it isn't is to switch off everything bar your modem/router to see if it changes. A drop from 9.3 to 2.4 is pretty severe so something must be happening then.
:)
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Sudden large changes like that are almost certainly due to electrical interference. The offending device may not be in your house of course, but the only way to prove it isn't is to switch off everything bar your modem/router to see if it changes. A drop from 9.3 to 2.4 is pretty severe so something must be happening then.
:)
thanks, okay so if i can determine the problem isn't at my property, i can get onto BT and complain ?
also, what kind of device could generate such SNR changes on my line ?
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thanks, okay so if i can determine the problem isn't at my property, i can get onto BT and complain ?
also, what kind of device could generate such SNR changes on my line ?
An old tv set, for example: https://www.bbc.co.uk/news/uk-wales-54239180
Do any of your neighbours experience issues?
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An old tv set, for example: https://www.bbc.co.uk/news/uk-wales-54239180
Do any of your neighbours experience issues?
nope, nothing internal in my property goes on or off at the times indicated on the graph .... most bizarre !
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nope, nothing internal in my property goes on or off at the times indicated on the graph .... most bizarre !
Unfortunately as seen in the article, it doesn't have to be in your property and can be VERY hard to narrow down if it isn't.