I think your reply is harsh, he didnt ask if he should stop worrying about it.
To the OP its definitely not normal, it would suggest maybe when the router/modem is more busy its increased power draw is interfering with the signal. Or possibly the device downloading to its higher processing is the source of interference.
I would make sure power cables are not tangled up with any other cables, if you have separate router/modem close to each other maybe move them further apart. IF these options are not available then do some diagnosis with swapping out equipment.
DLM wont care about your snr margin, it will only be bothered if your ES rates get too high or if you have too many lost sync events.
Also using BQM for diagnosis for this is not a good idea, downloading creates utilisation and yes can cause jitter, especially without bandwidth policies.
Why have you chose to not make your VDSL TBB BQM public?
Edited by Chrysalis (Tue 29-Mar-16 06:20:47)