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[LordSven]

Good day and merry festives to all.

Over the last couple of days I have been suffering sudden and dramatic drops in SNRm on my BT Infinty FTTC connection after a good two months of stable operation at DS 79+Mbps/US 18+Mbps.
I wonder if one of you expert folks (B'cat, Kitz etc) could take a look at my MDWS (LordSven) data and possibly give me a clue as to what might be causing the issue please?
DLM is already intervening, and I am now capped (I think) at 74760kbps down.

Hats off to the Zyxel VMG8924-B10A, which maintained sync to a SNRm of 0.5dB or less (thanks to Kitz info for suggesting it to me)!

Many thanks.

[j0hn]

Lots of noise between 1pm - 2pm on the 19th. The SNRM indeed plummeted and eventually caused a resync.
The line doesn't appear to be banded.
The max attainable is the same, and the SNRM a little higher than usual.
The attenuation is unchanged.
The Hlog/QLN show no significant change.

So my opinion is it was temporary noise (xmas tree lights is a big source at this time of year) and the line has returned to its normal state.
Your max attainable bounces up and down by a few Mb (between 74.5-78Mb). The line has resynced at 1 of the low points.
It will likely return to normal at the next resync.

[LordSven]

Thank you J0hn,

I had thought of Christmas lights but wondered if it could be any of my LAN side network kit (switches, xbox one, EE signalbox, etc?).
Had another episode today. Now banded I believe (from MDWS data).
This really sucks after such a long period of stability and excellent speeds.

Any furher observation/opinion welcomed!
Cheers

[LordSven]

Well, just resynced again and speed back up to 74Mb/s! I switched the router off for an hour or so after my previous resync switched it on with the RJ-11 disconnected, having left it off for over an hour, before re-connecting. All wired network equipment has now been disconnected from the VMG8924 in an attemt to isolate any possibility that my LAN side equipment was somehow at fault.
I wonder if there may be, or have been, some fault at the DSLAM/cabinet? Only time will tell I suppose.
The December timing of the appearance of these dramatic dips in SNRm would, perhaps lead one to consider Christmas lights but I'm not so sure.

Telnet pbParam data:
Status: Showtime
Last Retrain Reason:    1
Last initialization procedure status:   0
Max:    Upstream rate = 18266 Kbps, Downstream rate = 78821 Kbps
Bearer: 0, Upstream rate = 18266 Kbps, Downstream rate = 74328 Kbps
Bearer: 1, Upstream rate = 0 Kbps, Downstream rate = 0 Kbps
Discovery Phase (Initial) Band Plan
US: (7,32) (871,1205) (1972,2782)
DS: (33,859) (1216,1961) (2793,3959)
Medley Phase (Final) Band Plan
US: (7,32) (871,1205) (1972,2782)
DS: (33,859) (1216,1961) (2793,3959)
                  VDSL Port Details               Upstream                Downstream
Attainable Net Data Rate:           18266 kbps              78821 kbps
Actual Aggregate Tx Power:             7.6 dBm               12.9 dBm
====================================================================================
   VDSL Band Status    U0     U1     U2     U3     U4     D1     D2     D3
  Line Attenuation(dB):   5.8   26.1   40.0   N/A   N/A   14.2   33.2   51.5
Signal Attenuation(dB):   5.8   25.5   39.2   N/A   N/A   19.8   33.0   51.5
        SNR Margin(dB):    6.4    6.4    6.4    N/A    N/A    6.9    6.9    7.1
         TX Power(dBm):   0.4   -17.4   6.6   N/A   N/A   9.2   7.9   6.9

Would I be right in thinking that retrain reason is possibly indicative of the SNRm dips being interpreted by DLM as having a cause other than `my` line or equipment?