The tool below works out whether the dropout is your modem, your cables, or the NBN network itself — then walks you through the fix or tells you exactly what to say to your ISP.
NBN dropouts are caused by one of three things: a fault in your in-home equipment (modem or cables), an infrastructure fault outside your home on the NBN Co network, or network congestion at peak hours. Checking whether the lights on your NBN box change during a dropout tells you which one it is.
Watch the lights on your NBN box during a dropout. If they change, flash, or go off, the fault is on the NBN network — your ISP needs to lodge a fault with NBN Co. If the lights stay solid and unchanged, the fault is in your modem, cables, or settings.
Yes. A faulty or loose ethernet cable between the NBN box and modem is one of the most common causes of frequent dropouts. Replacing it with a new Cat6 cable (under $10 at Bunnings or Officeworks) often fixes the problem immediately.
Dropouts only at night between 6–10pm are almost always network congestion — your ISP's infrastructure is overloaded at peak hours. This can't be fixed at home. Contact your ISP or consider switching to one with better evening capacity.