@brookecouchman
Thanks for the advice. After insisting that the fibre outside my house was working fine and not subject to an outage, I finally convinced the AGL service assistant to call the NBN and arrange for my NBN box to be tested/replaced. As I suspected, the box was fried in a lighting storm the week before. As soon as it was replaced everything worked again as normal.
I wasted all that time (over a week), and would still be waiting had I not persisted and asked for the NBN box to be tested.
I'm pretty disappointed at how inconsistent the advice had been, and the lack of technical competency in AGL's technical help desk.
