Reading your 1st post again, I've just got even more confused.
The download/upload figures appear to be mixed up.
I've no idea if the SNRM figures are also mixed up.
Do you have another modem with more detailed stats?
DSL Uptime
1 days 21 hours 13 minutes 47 seconds
DSL Type
VDSL2
DSL Mode
Interleaved
Line Rate
20 Mbps 55.4 Mbps
Data Transferred
1197.11 MBytes 1171.56 MBytes
Output Power
4.7 dBm 4.7 dBm
Line Attenuation
0 dB 0 dB
Noise Margin
6.9 dB 6.3 dB
ukhardy07 (knowledge is power)
Tue 29-Aug-17 18:39:32
Did you mix up the upstream/downstream in the 1st post?
The most recent stats suggest:
Upstream - 6.9dB
Downstream - 6.3dB
Which looks correct. The Upstream is above the 6dB target as you are at the 20mb package limit. The downstream being 6.3dB is close enough to 6dB, and actually what my line syncs at every time.
Speed loss is likely due to crosstalk, interference from neighbouring lines. Probably not banded with 6.3dB snrm but watch the "Line Rate 55.4 Mbps" figure after the next couple resyncs and see if it changes.
You're probably not missing much over that 5mbit you've lost. I think just forget about it and look forward to newer tech in a few years to give a big boost (gfast, etc).
I very much doubt you'd notice the difference between 61mbit and 56mbit. Especially over wifi or similar.