1. DLM tweaks seem to only force a modem re-sync.
2. The BT HH3 doesn't always notice the modem re-syncs.
3. The IP profile seems to only reset in response to the HH3 rebooting the session.
In any case; after several months getting download speedtest results around 64-65Mbps (and an IP profile around 68-69Mbps), I decided that if everything was now stable, I may as well force a Internet session disconnect/connect (via the HH3 web-pages).
That was yesterday.
At precisely midnight, last night, my HH3 logged a disconnect (session time counter reset to zero at midnight).
I'm now back where I was constantly from 80/20 product roll-out, right up to whatever event dropped my profile by 12% (the actual event dropped the profile to around 55Mbps, but it gradually recovered a little and had been stuck at around 68Mbps for months - I figured cross-talk and assumed DLM had recovered as much as it was going to)...
Either that or the wonderful World of vectoring has arrived in sunny Banbury (some hope )
Download speed achieved during the test was - 75.63 Mbps
For your connection, the acceptable range of speeds is 60 Mbps-77.43 Mbps .
IP Profile for your line is - 77.43 Mbps
So; an IP profile of 77.43Mbps equates to a full 80Mbps connection speed.
vDSL2 FTTC Infinity with BT
DL Sync 78Mbps
UL Sync 20Mbps