Why might my SNR margin stats suddenly change like this ?

Note the SNR Margin change down/up. There was heavy rain this morning, so I might just know the answer. The average throughput is the same and the line is stable. Does this bode ill for the future however ?

I do notice that my parents, who live next door, with the same pole, same cabinet, and almost the same sync speeds/thoroughput as I have, although their SNR margins are 13/10 dB down/up. They are with Vodafone.

From:

DSLAM/MSAN type: BDCM
Modem/router firmware: Not reported
DSL mode: G.993.2 (VDSL2)
Status: Showtime
Uptime: 40 days, 0:57:55
Resyncs: 0 (since 21 Apr 2017 10:13:35)

Downstream Upstream
Line attenuation (dB): 14.9 6.0
Signal attenuation (dB): Not monitored
Connection speed (kbps): 39999 7448
SNR margin (dB): 4.8 6.7
Power (dBm): 14.0 7.4
Interleave depth: 4 0
INP: 52.00 0
G.INP: Enabled

RSCorr/RS (%):
RSUnCorr/RS (%):
ES/hour:

To:

DSLAM/MSAN type: BDCM
Modem/router firmware: Not reported
DSL mode: G.993.2 (VDSL2)
Status: Showtime
Uptime: 41 days, 5:14:25
Resyncs: 0 (since 21 Apr 2017 10:13:35)

Downstream Upstream
Line attenuation (dB): 14.9 6.0
Signal attenuation (dB): Not monitored
Connection speed (kbps): 39999 7448
SNR margin (dB): 13.7 10.2
Power (dBm): 14.0 7.4
Interleave depth: 4 0
INP: 52.00 0
G.INP: Enabled
RSCorr/RS (%):
RSUnCorr/RS (%):
ES/hour:

Either some noise has switched off which was interfering with your signal or the rain has wet a joint and it is now connecting better.

Your target is much better now, but I would wait and see if it drops again when the rain stops.

or the rain has wet a joint and it is now connecting better.

Wet connections do not improve things on the whole.

Yes,

I noticed that my parents, who switched to vodafone about 3 weeks ago from ADSL Max from Sky, had the same 13/10 dB SNR down/up during the first 10 days and after that still the same SNR with a sync of 39995/9999. Which made me a little jealous. Their speed tests are overall faster than mine.

So either something rather good has happened, and I might get better throughput (even a decent 80/20 profile sync !), or I have a waterlogged line which will start to flake out sometime in the near future, BTO round, moan moan. BTDT.

Your downstream sync suggests a hard 40Mbps cap, which means you are either on a 40/10 service or DLM has capped it at that due to earlier problems. Your attenuation suggests you should be able to get well over 60Mbps.

In either case your upstream sync stinks. It should be up at 9999kbps on 40/10 or higher if on an 80/20 connection.

In reply to a post by RobertoS:

Your downstream sync suggests a hard 40Mbps cap, which means you are either on a 40/10 service or DLM has capped it at that due to earlier problems. Your attenuation suggests you should be able to get well over 60Mbps.

In either case your upstream sync stinks. It should be up at 9999kbps on 40/10 or higher if on an 80/20 connection.

I'm on Zen Unlimited fibre 1 up to 38. I've been on UL fiber 2 before. I saw a maximum of 51Mb downstream for 3 days. It was stable and fast, but the ES/hour were eyebrow raising. It tried 48, 46, 42 .. then settled for 40. I've seen it Sync at 9999 up, but the D/S Sync often drops proportionately I went from 35.5 D/S to 39999 when the lower SNR target was rolled out.

However my line stats have improved since I first got fibre according to the BTW ADSL checker:

VDSL RANGE A DS CLEAN HIGH 64.3 LOW 49 US: HIGH 17 LOW 11.2

VDSL RAGE B DS IMPACTED HIGH 52 LOW 32.4 US: HIGH 14.1 LOW 6.9

A stable 50 down would make me a fairly happy bunny.

heh it just went back to this:

Stats recorded 15 May 2017 18:09:03

DSLAM/MSAN type: BDCM
Modem/router firmware: Not reported
DSL mode: G.993.2 (VDSL2)
Status: Showtime
Uptime: 41 days, 7:13:25
Resyncs: 0 (since 21 Apr 2017 10:13:35)

Downstream Upstream
Line attenuation (dB): 14.9 6.0
Signal attenuation (dB): Not monitored
Connection speed (kbps): 39999 7448
SNR margin (dB): 4.8 6.4
Power (dBm): 14.0 7.3
Interleave depth: 4 0
INP: 52.00 0
G.INP: Enabled

RSCorr/RS (%):
RSUnCorr/RS (%):
ES/hour:

Central heating kicked in? Cooking? TV switched on? (Any in the house if you have multiple ones). Anything at electrical that goes on and off.

I wonder if the maths in the router just went a little screwy and calculated it incorrectly?

The answer is certainly noise, but the question remains - what noise?

When pondering this new question, don't forget that crosstalk is a primary consideration in FTTC: it could be caused by someone turning their own modem on and off overnight, or when on holiday.