Get online support
Hi Emmitq96
TPG does not support third party devices, however you many need to check the google solutions
https://support.google.com/googlenest/thread/20976528?hl=en
See the details of your NBN HFC settings.
https://community.tpg.com.au/t5/Broadband-Internet/VLAN-info-for-NBN-HFC/td-p/33210
Morevover you can bridge the TPG modem and use your nest as a wireless router.
Hope that helps
Thanks