If memory serves, I believe you have experienced "issues" on your connection right from the off, haven't you?
What looks strange (apart from eDMT reporting downstream data in band D0, D1, D2 rather than more familiar D1, D2, D3) is that despite the low sync & atainable speeds, you do still seem to be achieving SOME bit-loading in the highest frequency band.
The higher DS band is usually discoverd, but completely unused on such low sync speed connections.
Do you perhaps have a HG612 to try on your connection, to obtain an alternative data set & compare stats with your ECI modem?
Do you have any records of ongoing changes, error counts, noise levels etc?
Your SNR graph, although plotted more horizontally, data-wise looks quite similar to mine at the lower frequencies (see attached).
Worryingly, your SNRM levels suggest you are currently achieving the max that your connection can physically handle.
Have your attenuation values also altered over a period of time?