The Attainable/max Rate calculation on the modems is usually a load of rubbish, I think on some of them it assumes an SNRM of 0
I've even seen cases where one of the technicolor routers (Can't remember if it's a 585v7 or a 582n) was showing an attainable rate that was much lower than what the line is actually syncing at.
If you believe my HG612 my FTTC line can do 104/34 if it was allowed to, when I first put an unlocked modem on the line it was showing something like 130/40, It would be interesting to see what it would actually sync at if BT did uncap the VDSL profiles.
Attainable rate (kbit/s) 104788 34006
SNR margin (dB) 12.9 15.2
Line attenuation (dB) 0 0
Output power (dBmV) 13.2 -1.6
Statistics
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Path 0
Path 1
Downstream Upstream Downstream Upstream
Line rate (kbit/s) 79987 19999 0 0
CRC errors 0 0 0 0
FEC errors 93 42 0 0
HEC errors 255 0 0 0
