Assuming that you are using the two box solution, as shown in your signature block, then the DLM process will only be interested in the stability of the link between the VMG1312-B10A and the DSLAM. It (the DLM process) will have no knowledge of (or interest in) the Asus router.
If the modem has undergone a number of power cycles, thus link re-trains, then I wouldn't like to attempt to guess when the DLM process will decide that the link is stable.