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[burakkucat]

It's the 1st and only time I've seen G.Fast run below the target SNRM and it's both the upstream/downstream.

That is what caught my eye.

[adslmax]

Been contact with isp about low snr on downstream but he told me to keep an eyes on it as if went lower than 2db it might be unstable but at the moment they ran the test and found no fault or no issues at all. He also saying there isn't any change in Openreach DLM to lower snr as it still on 3dB default but he told me there is other customer on g fast got lower snr at 1.9dB.

[burakkucat]

. . . at the moment they ran the test and found no fault or no issues at all.

That is good to know.

He also saying there isn't any change in Openreach DLM to lower snr as it still on 3dB default but he told me there is other customer on g fast got lower snr at 1.9dB.

Thank you for sharing the information.

[adslmax]

Updated:

G.fast has lost the connection overnight as I check the dslstats as it seem it revert back to 3dB snr now.

Stats recorded 27 Aug 2021 19:23:41

DSLAM type / SW version:   BDCM:0xc190 (193.144) / v0xc190
Modem/router firmware:     AnnexA version - A2pvfbH045o.d27j
DSL mode:                  G
Status:                    Showtime
Uptime:                     16 hours 4 min 42 sec
Resyncs:                   0 (since 27 Aug 2021 19:22:10)
         
            Downstream   Upstream
Line attenuation (dB):     40.5      0.0
Signal attenuation (dB):   40.5      0.0
Connection speed (kbps):   201875      26895
SNR margin (dB):           3.1      3.1
Power (dBm):               0.0      4.0
Interleave depth:                
INP:                       550.00      540.00
G.INP:                     Not enabled      Not enabled
Vectoring status:          Not monitored      

RSCorr/RS (%):             0.0076      0.0053
RSUnCorr/RS (%):           0.0000      0.0000
ES/hour:                   0      0

[Alex Atkin UK]

At least we now have an idea of just how much a difference 1dB can make on g.FAST, very interesting.

[adslmax]

I do remember the old day on ADSL2+ set SNR at 1.5dB manual  but can't do that on FTTC or G.fast

[Alex Atkin UK]

Mine was never stable below 3dB, especially upstream had to remain 6dB.

[j0hn]

I do remember the old day on ADSL2+ set SNR at 1.5dB manual  but can't do that on FTTC or G.fast

Has it been attempted on G.Fast?

Has anyone tried this on the Vigor 166?

[meritez]

At least we now have an idea of just how much a difference 1dB can make on g.FAST, very interesting.

36mb/s lost!

[adslmax]

That's my G.fast according to dslstats downstream snr v connection rate over 7 days (best highest stats with line atten of 38.8dB with 2.1dB)

4.0dB - 212Meg
3.6dB - 218Meg
3.2dB - 224Meg
2.8dB - 230Meg
2.4dB - 236Meg

stats right now:

Downstream   Upstream
Line attenuation (dB):     38.8      0.0
Signal attenuation (dB):   38.8      0.0
Connection speed (kbps):   226531      32165
SNR margin (dB):           3.1      3.1
Power (dBm):               0.0      4.0
Interleave depth:                
INP:                       550.00      540.00
G.INP:                     Not enabled      Not enabled
Vectoring status:          Not monitored

** very interesting here **

The drivers between these two below are worse and better on downstream / upstream with line atten

Better downstream / upstream with line atten 38.8dB: 226/32
DSLAM type / SW version:   BDCM:0xc190 (193.144) / v0xc190
Modem/router firmware:     AnnexA version - A2pvfbH043q.d26u

Worse downstream / upstream with line atten 40.5dB: 201/26
DSLAM type / SW version:   BDCM:0xc190 (193.144) / v0xc190
Modem/router firmware:     AnnexA version - A2pvfbH045o.d27j

[adslmax]

Overall disappointed with G.fast due to change overnight why snr of 6dB?


Stats recorded 01 Sep 2021 20:32:28

DSLAM type / SW version:   BDCM:0xc190 (193.144) / v0xc190
Modem/router firmware:     AnnexA version - A2pvfbH043q.d26u
DSL mode:                  G
Status:                    Showtime
Uptime:                     17 hours 3 min 39 sec
Resyncs:                   0 (since 01 Sep 2021 03:29:25)
         
            Downstream   Upstream
Line attenuation (dB):     40.4      0.0
Signal attenuation (dB):   40.4      0.0
Connection speed (kbps):   171923      19475
SNR margin (dB):           6.1      6.2
Power (dBm):               0.0      4.0
Interleave depth:                
INP:                       551.00      535.00
G.INP:                     Not enabled      Not enabled
Vectoring status:          Unknown      

Updated can see BTw checker as G.fast estmate has changed:


High   Low   High   Low         
VDSL Range A (Clean)    80   71.9   20   19   66.7  Available   Available
VDSL Range B (Impacted)    80   69.7   20   19   63.5   Available   Available
G.fast Range A (Clean)    177.3   142.1   24.4   9.5   121.6  Available   Available
G.fast Range B (Impacted)   138.3   91.5   15.5   7.3   82.1   Available   Available

[burakkucat]

Uptime:                     17 hours 3 min 39 sec
Resyncs:                   0 (since 01 Sep 2021 03:29:25)

There was a re-train at 0329 hours this morning.

      
            Downstream   Upstream
SNR margin (dB):           6.1      6.2
G.INP:                     Not enabled      Not enabled
Vectoring status:          Unknown      

The end result is a SNRM of 6 dB, with G.INP disabled and vectoring status unknown. 

Something is not right. 

I do not have sufficient knowledge of G.Fast to be able to make any suggestions.

[adslmax]

Discovery Phase (Initial) Band Plan
US: (348,1267)
DS: (342,1096)
Medley Phase (Final) Band Plan
US: (348,1267)
DS: (342,1095)
VDSL Port Details               Upstream                Downstream
Attainable Net Data Rate:        19124 kbps             172092 kbps
Actual Aggregate Tx Power:          4.0 dBm                 0.0 dBm


The vector has disappear!

[mofa2020]

Vectoring status changed from Not monitored to Unknown

[meritez]

If it's bothering you, call unchained and ask to be downgraded to 160/30.

G.fast can be very unpredictable, I have a customer who pays for 330/50 and the line can sync at anything between 200 to 309 down and 30 to 50 up.

Downgrading may be better than dealing with the headache of a variable digital subscriber line.