Have you read the manual?
What settings have you tried?
Set WAN access type to VDSL router and enable tagged vlan.
The settings are PPPoE, TPG username with @TPG.com.au on the end, password, and VLAN ID=2.
You can check the username and password by logging in to Post Office on your mobile phone.
For VLAN ID, set Internet VLAN ID=2 in Triple-Play section.
In interface traffic type section, set each lan port, wireless and wireless guest zone to Internet.