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jsbrown724
Level 3: Gumshoe

Large Sync speed variances on FTTN connection

Answered
Following on from a previous post (https://crowdsupport.telstra.com.au/t5/Modems-Hardware/Increasing-dropouts-since-Firmware-Upgrade-18...) have had ongoing issues with drop outs and sync speeds.
 
Connection is FTTN, approx 250M from pillar and node (thankfully alongside each other) and capable of obtaining 100/40 speeds.  NBN connection has been operating fine for almost two years.  Internal wiring is single point, Cat5 to building entry point.
 
Normal connection is -
 Max Line Rate:  51U 120D
 Line Rate: 40U 109D
 Line Attenutation: 4.1, 17.3, 26.3 Up and 9.1, 21.9, 34.3 Down
 Noise Margin 12 Up and 8.7 Down

I then find fluctations in line rate, attenuation and Noice Margin with them jumping about all times of the day starting from 12 Nov -
Line Rate: 40U 91D
Line Attenuation: 4.1, 17.3, 26.3 Up and 9.1, 22.0, 34.3 Down
Noise Margin 12.7 Up and 5.1 Down
 
This resets upon a reboot and then after that see the speeds move up on a dropout to the max and then basically renegotiate downward to the 40U 91D each day.
 
Get to thursday 5/12 and find the following -
 Max Line Rate: 19D 23U
 Line Rate: 19D 22U
 Line Attenuation: 15, 28.2, 36.7 Up and 18.6, 32, 44.6 Down
 Noise Margin: 7.1 Up and 6.1 Down
 
Contact Support and run through all the tests, reboot, factory defaults etc.  No change and NBN appointment booked in.  Overnight it goes back to original settings and Friday morning 6/12 again drops to values well out of the normal range.  Same thing happens Friday night, back to normal.
 
NBN Tech came out today (Sat 7/12) and indicated that my line voltage was too high and as a result removed the connection back to the exchange (who knew once NBN connected that was still there).  Note that when they came out the line was still at 100/40 max and as per what would be "normal" historically for my connection.
 
An hour after the Tech leaves, my connection drops to sub par performance again and back on the phone with Support.  Run through the same tests, do a few more checks and a stability profile is applied to address the dropouts.  Not sure if it is on, as I do know these can take some time to apply.
 
So curent connection is -
 Max Line Rate: 18.75D 80.64U
 Line Rate: 18.75D 75.98U
 Line Attenuation: 19.3, 28.2, 36.7 Up and 18.6, 31.9 and 44.5 Down
 Noise Margin: 6.2U and 7.3D
 
Looking for thoughts and suggestions.  There is clearly something causing the fluctations in Line Attenuation and Noise Margin and it has only happened recently.
 
Thanks.
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Level 24: Supreme Being
Level 24: Supreme Being
Accepted Solution

Re: Large Sync speed variances on FTTN connection

It looks like there is a intermittent line fault that is gradually getting worse. The 10 dB drop in both up and down would account for your current speed drop. It doesn't look like the stability profile is active yet as the noise margin is still below 12 dB. On a normal connection the equipment aims for a minimum noise margin of 6 dB but when a stability profile is applied the equipment tries to maintain a minimum noise margin of 12 dB.

I suspect there is a faulty connection in one of the pits, connection pillars or the node.

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3 REPLIES 3
Highlighted
Level 24: Supreme Being
Level 24: Supreme Being
Accepted Solution

Re: Large Sync speed variances on FTTN connection

It looks like there is a intermittent line fault that is gradually getting worse. The 10 dB drop in both up and down would account for your current speed drop. It doesn't look like the stability profile is active yet as the noise margin is still below 12 dB. On a normal connection the equipment aims for a minimum noise margin of 6 dB but when a stability profile is applied the equipment tries to maintain a minimum noise margin of 12 dB.

I suspect there is a faulty connection in one of the pits, connection pillars or the node.

View solution in original post

jsbrown724
Level 3: Gumshoe

Re: Large Sync speed variances on FTTN connection

Thanks @cf4, I did ask the Tech about the joints etc, but given his first test identified the voltage that was what was changed.  Appreciate they want to remove one issue at a time.

 

Service reconnected an hour ago from this post, and back to 100/40.  This reconnection took quite some time!  Support are supposed to be monitoring this for 24h so will see what comes of the update tomorrow.

 

AE243452-B86C-47CE-8939-CC7CD4CCFE45.jpeg

jsbrown724
Level 3: Gumshoe

Re: Large Sync speed variances on FTTN connection

After a couple of NBN visits they finally found a fault at the pillar!

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