Hi again Swal,
I am not aware of any regular time-related DSLAM happenings other than single changes often in the early hours. Perhaps B_E1 or BKK might have other ideas?
If you have a co-operative neighbour, might I suggest you run an extension lead from next door. Then, during the disturbance, trip the main breaker(s) for all your supplies FIRST, then plug your modem in, then router, then computer(s) into the next door supply. If there is no change disconnect your items from the extension lead FIRST then replace your items as normal and ask if the next door would trip their supply for the converse test.
Woops auto-correction undetected !
Can you devise some other tests if perhaps the neighbour has a VDSL service too ?
How about lending your modem to next door and observing the graphs from there ?
In VDSL matters, I am never surprised by an outcome, but surely this must be some form of RFI ?
Kind regards,
Walter