I'm assuming you mean the lack of figures in the graph labelled 'Signal to Noise Ratio' rather than 'SNR per tone'.
Yes, that's the one. It does report SNR on the y axis per tone on the x axis.
I've looked through my past graphs, and there seems to be no rhyme nor reason as to when the upstream SNR per tone is displayed. It certainly doesn't seem to follow a resync on my own connection and can be a wee bit random. I even have a couple of graphs when it displays just some of the upstream bands (see attached).
During the period I was logging it seemed to report 0db in approx 1:5. I'm therefore wondering if its a 'feature of the HG612 on ECI Dslams' were perhaps a figure isn't returned every-time. This is what I meant when I said "but I notice its sometimes there in HG612ModemStats too."
The fact that its not reported sometimes on other connections too, gives me some assurance that its more likely that for some reason or other it returns a 0 figure.
From what I have witnessed, whenever US SNR, QLN & Hlog per tone are reported following a resync (not every resync though), it continues to be reported dynamically until the next resync, when it might cease until the next resync & so on.
The fact that on your connection, sometimes the lower frequency
SNR per tone data is completely absent yet higher frequency US per tone is still reported does seem to further confirm the line fault.
We have also seen your US
SNRM per band graphs where the plots cross over & demonstrate other unusual behaviour over time.
I have never seen any of these issues previously & I have studied plenty of data & graphs from quite a number of VDSL2 connections (from the very best, to the very worst).
So no, I don't believe that what you are witnessing is anything at all related to a
'feature', rather it is clear proof of an intermittent fault.
Additionally, the issues you are now experiencing with telephone communications & the effect they are having on your VDSL2 service further reinforces the fault theory.
It really is a shame that the recent engineer's visit wasn't more fruitful, as it has just prolonged the inevitable.
With a bit of 'luck', you will soon completely lose broadband and telephone services as the SLA for reinstating telephone services should then kick in & the fault will
have to be located & repaired within a reasonable timescale (unless there is actually more than one fault
).