There is an explanation of what the stats mean here:-
http://www.kitz.co.uk/adsl/linestats_explanation.htmThat page does contain links to further explanations.
The details are for ADSL connections but many of them are still relevant for VDSL2 (FTTC) connections.
ADSL connections use Super Frames (SF) The VDSL2 equivalent is OverHead Frames (OHF).
WWWombat over on the TBB forum has provided quite a detailed explanation for some of the other stats, particularly related to Interleaving.
Regarding SNRM, the target at sync time is 6 dB for VDSL2 connections, to allow for sufficient downward fluctuation during 'noisy' periods, usually in the evenings & lasting until daylight hours.
Some connections fluctuate quite a lot & some only fluctuate by very small amounts.
Resyncing whenever SNRM is at its peak usually delivers higher sync speeds, at the expense of seeing more errors that can actually slow down throughput etc.
Some connections have very high SNRM levels.
This is either because DLM has taken action following a burst or bursts of errors & has capped/banded sync speeds at a lower level.
When this is the case, attainable rates are usually much higher than sync speed.
Another scenario for high SNRM levels could be a connection with a short D-side but the user has opted for a 40 Mb service.
Attainable rates could be much higher (say up to 125 Mb, but as the connection is capped at 40Mb, SNRM could be as high as 30 dB or so, showing plenty of margin for speed increase if the user chose to move to an 80 Mb service.
Basically, an ideal connection would have spare SNRM, be on fastpath (D: value as shown in the raw data stats of 1) & with very few error counts.
FEC/RSCorr errors kick in when Interleaving is applied, improving stability & INP (Impulse Noise Protection) at the expense of some sync speed.
DLM fully controls this aspect, based upon continual connection monitoring & making adjustments whenever it deems it to be necessary.
Unlike ADSL connections, at the moment, ISPs have no control whatsover over Interleaving levels & cannot adjust SNRM levels.
As my connection could happily run with SNRM as low as say 3 dB (it hardly fluctuates at all - even overnight), I could achieve higher sync speeds if the target was lowered.
Bursts of massively increased errors (whether random or with a timed pattern) tend to suggest a REIN issue, but could just as well be caused by an intermittent line fault such as a corroded cable joint etc.
My connection experienced that issue from a poor underground cable to pole monted DP (Distribution Point) joint.
As the weather became hotter & dryer, the error counts would shoot through the roof & the connection would randomly & frequently resync.
DLM didn't like that & would regularly cap/band my connection at very low sync speeds in order to attempt to provide some stability (as low as 8 Mb for a while).
Permanent 'noise' increase (as portrayed via the QLN graph (Quiet Line Noise), tends to suggest increased croosstalk from other users' connections, possibly due to naturally induced interference from other cables within a D-side bundle or more rarely, due to cable damage/water ingress.
I hope that helps somewhat, but please feel free to ask specific questions - we may be able to answer them between us.