well its probably because the snrm is below 6db, its only slightly below so unless your snrm is unstable I wouldnt expect your line to drop.
my hg612 always reports an attainable at least 1mbit higher than my sync when I first sync up and the snrm is always at least 6.5db at that point likewise.
the last week or so my attainable has been slowly drifting downwards so I am now at.
Max: Upstream rate = 34053 Kbps, Downstream rate = 71140 Kbps
Path: 0, Upstream rate = 20000 Kbps, Downstream rate = 70911 Kbps
So if I resynced now knowing my line seems to want at least 6.5db and a buffer of 1mbit below the modem attainable I suspect my sync speed would be about 70.1mbit at the max, although its possible bitswapping has disabled some tones so on a new sync those would be available again.
BT Infinity 2 Since Dec 2012 - BQM
Edited by Chrysalis (Wed 18-Sep-13 16:52:53)