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[silus]

About a week ago, Openreach fixed my fttc line by moving my cable to a different, lesser used one between the DP and the green cabinet. This had the effect of reducing the line attenuation value, giving me a significant boost to sync speed up & down, and eliminating CRC, ES, and SES errors I was getting.  They did not perform a DLM reset at the time.

Since then, my line has resynced in the early hours of each morning every single day, during the hours when DLM normally makes its changes. I was expecting perhaps DLM might see the cleaner line and change the SNR or interleaving putting it back to fast path etc. But every time it resyncs, none of the line settings have changed at all.

Why would it be forcing a resync every morning, is this normal DLM behaviour if there hasn't been a DLM reset after work to significantly improve the line?  Do I need to try and convince them to do a reset for it to completely re-train my line after that work they carried out?

thankjs

[kitz]

No harm asking for a reset.  Advise them that the new line seems stable with better stats but no reset was done at the time. 

I cant give you an answer what it is doing each morning - its worth checking not just the SNRM or switch between Fast/Interleave. Changes to the depth of Error protection may not be as obvious.  Even when interleaving is in effect off the line will still be on the Interleave Path.  Also check for any changes in the depth of interleaving and INP

[j0hn]

If absolutely NONE of the line stats are changing then it won't be the DLM resyncing the line. It only resyncs when it's changing the current line profile.
As kitz points out some of the changes made by the DLM are very small, tweaking G.INP values, the amount of error correction or changes to the interleaving depth/delay. Without very detailed line statistics that are only available on certain modem chipsets then you wouldn't notice some of these DLM changes.

It could be an external noise source (machinery, sewage/water pumps, etc) turning on around the same time everyday that is causing the line to resync. It can even be a neighbouring line connecting around the same time each day as that can cause a big enough SNRM drop to knock a line out of sync.
Your new pair will be in a different position within the multipair cable or may even connect back in to a different cable bundle further towards the cabinet, explaining why it's only effecting the new pair and not the old.
Crosstalk and interference can vary considerably between different pairs.

The DLM also no longer has a specific time window that it applies changes. As FTTC take up grew the time window that the DLM made changes to lines gradually grew.
The DLM can change the line profile at pretty much any time of the day now, though it is still overnight most of the time.

Ask your provider for a DLM reset. Some will happily accommodate this while others won't entertain the request if your line is meeting your contracted estimates.

What type of modem are you using? If it's a Broadcom chipset with access to the full Broadcom CLI then I recommend running DSLStats to capture detailed minute by minute starts off the line. It might catch whatever is causing the resync or might pin point what changes the DLM is making (if it is the DLM).

[silus]

So the upshot with this is it seems it was DLM got itself in a bit of a state with the daily resyncs. None of the dsl settings were being changed at all (at least the ones my ASUS router would show me).

I asked sky for a dlm reset and so far had 3 days of no resyncs, then the expected resync this morning where it did change stats starting to come down from the reset 6db snr.

Would expect another 2 resyncs over the next few days with a day in between while it comes down to 3db based on prior resets, but so far it seems to be going as expected and having any days of no resets is a good sign it’s fixed.

Strange that it would have gotten itself in such a state after openreach fixed my line, just glad it was an easy fix. Line should hopefully tide me over now until such time as someone is kind enough to roll fibre out here

[j0hn]

So the upshot with this is it seems it was DLM got itself in a bit of a state with the daily resyncs. None of the dsl settings were being changed at all (at least the ones my ASUS router would show me).

If it's an Asus DSL-AC68U (or any with a Mediatek chipset) then it makes a better door stop than it does a modem. Having used about a dozen modems on my FTTC line nothing came close to the uselessness of my Asus.
I've never seen Openreach blacklist any other modem from certain DLM functions (they blocked G.INP on these devices for a long time).

The newer Asus modems (in the last couple years or so) have a great Broadcom chipset.

I daily run an Asus router.

[silus]

It is a dsl-ax82u - I believe this has a Broadcom chipset?