the speed is interesting as the 1mb fixed is 1152kbps
I don't know how DLM works but here's a thought, since on ADSL2+ they don't set profiles and can't control the SNR margin of my connection (because of the router) is it possible that the DLM forces an increased Attenuation? As it's only on ADSL2+ that I get the larger than normal Attenuation, and on the other modulation types I get the 1mb cap. Just some speculation, I have no idea as to the working of DLM on these matters.
the attenuation is not changed by the DLM but it is often the case that using adsl2 increases your attenuation by up to 2db
have you thought about resetting modulation to adslmax
just read old posts and were you not on half mb fixed at start?
Fixed was when I had the issue but normal speeds were 0.75Mb. As I mentioned, recently the engineer came out and put the line on a shorter loop from the DP. Attenuation dropped to 75dB, new speed was 1.5-1.6Mb.