The NBN would most likely be down at many different places at any given time and recent weather and fire events would most likely have made matters worse. What did Optus say or not say about your poor NBN connection?
Is it back up now, DannyR? There are no reported outages in 5108.
As Yeldarb suggests, the more detail you can provide the better the changes Yes Crowd may be able to help 🙂