I have the top tiered plan (100) and it was working fantastic since NBN was installed a year(ish) ago. But the past week has been horrible!! Dropouts and soooooooo slow to load up any page. But nothing showing in the Network Status as having issues. Have reset the router/modem, changed ethernet ports - anything I can think of - but it's still crap. So frustrating.
I know NBN is not under your control, but have you had other people on the top plan having similar issues lately?