Welcome to TPG Community!
Have you check if service is on outage?
If new service could you confirm the proper set up of the internet devices?
Try a reset of the NBN HFC NCD (Network Connection Device - Black Box Arris). On the back of the NCD-Black box there is an reset button (needs a pin clip to press) Press this and count to five, all LEDS should go out and then reset to green. Once Modem gets WAN connection, then retry web browsing. " Watch our short video guide on how to set up your NBN HFC service. Visit https://link.tpg.com.au/tsaoQD "