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Hi @wasif_zafar
In order for the setup that you've tried to work, you need to make sure that the NBN technology that you are using is FTTP (Fibre to the Premises) as it won't work on other technology, unless your computer can setup a VLAN ID.
For the device to authenticate, it requires the correct TPG username and password.
The general settings needed for authentication is listed here.
BasilDV