I’ve recently switched to Spark NZ fibre broadband. I was previously on Big Pipe (which is also Spark, but their cheap broadband, which also exists for some reason). Anyway, the switch happened this morning and pandemonium ensued as “there’s no internet!”
The issue was the settings on the Spark fibre network are slightly different to the Big Pipe network. In the Amplifi app, click on the image of the router, go into the “Internet” section of the settings, turn on VLAN ID and set the VLAN ID to “10”.
Otherwise you won’t be assigned an IP address.
Hopefully this is helpful for someone in the future.