We don't normally support NON-TPG supplied modems, but we try to help when we can.
We recommend using the supplied TPG modem for the best support and guaranteed working service.
A quick look on the netgear website, shows this may be a router only, and not a modem/router.
It will mean you may need to use this as a wifi access point in conjunction with the TPG modem.
You may need to source further help from netgear.
Thanks to my understanding it can be set up either way, The TPG supplied router does not give me wifi even through one brick wall hence the need to extend with a mesh system however still slower than it could be I think using it as an access point rather than router .