If your DS SNRM is of the order of 16 dB then something is not correct with your circuit.
Which device are you currently using as CPE? The BT-HH5 or the TP-LINK VR900?
I am very wary of the BT-HH5, as it has had problems from the first day of its release. Its biggest problem was spontaneous rebooting, often many times in a day and so much so that the DLM assumes the line is faulty . . . .
There is one technique that I have suggested to others, previously, and that is at the end of the day to power down the modem & disconnect the lead linking the device to the filter (centralised or micro, as the case may be). Leave the device in that state overnight and only power it up & reconnect it when you next need Internet access. Sometimes by leaving the DSLAM's line-card port in a quiescent state, allowing it to "relax" overnight, can clear an abnormal state of the circuit.
Please note that the above technique should only be performed once . . . Do not use it each and every night!