For Google wifi, it won't work if you connect it directly to the Arris as NBN HFC requires a VLAN which google wifi doesn't have.
You may use your google wifi as a router or wireless repeater together with our TP-Link VR1600v which has the VLAN that NBN Requires.
Please try the follow my recomendation below.
After saving turn off your google wifi and connect it to our TP-Link VR1600v Router
Make sure you use the WAN Port of your google wifi.
Turn your google wifi on and try the internet
Let us know if this work.