OK bad news, you are on an ECI cab which means no G.INP assistance to improve speed.
Speeds can get lower due to crosstalk, that is interference from one line to an adjacent one, or in the Technobabble this:-
"In electronics, crosstalk is any phenomenon by which a signal transmitted on one circuit or channel of a transmission system creates an undesired effect in another circuit or channel. Crosstalk is usually caused by undesired capacitive, inductive, or conductive coupling from one circuit or channel to another."
I realise this will be no help to you and your ownly option is to keep reporting when your speed is less than the guaranteed rate in the hope it can be improved.
