"PPPoE connection is down" - what does this mean?
Keeping things at a very basic level, there are two fundamental components of a G.993.2 (VDSL2) based Internet service. The first is maintaining the DSLAM and the modem in a synchronised state. The second is achieving and maintaining a
Point-to-
Point
Protocol
over
Ethernet session with the CP providing your Internet service. It is the latter which was observed to be "down" or "absent".
Having looked at your circuit's recent behaviour (via MDWS) I have (very tentatively and without any hard & fast real, physical evidence) come to the conclusion that there is a defective connection (joint) somewhere in the circuit. Such a defect will account for the numerous resynchronisation events we have witnessed and whenever such an event occurs the PPPoE session will, ipso facto, also be lost. (If I was tasked to fault-find and then fix your circuit, I would find that evidence of multiple resynchronisation events to be most useful knowledge . . . As shown by the blue trace in the second image I have attached, below.)