Welcome to the Community!
We have an article on how to use/set up the TP-Link VR1600v modem:
We have detected that your internet is up and running for more than a day now.
You may check the default Wi-Fi password on the sticker at the back of the modem.
Should you require further assistance, you may reach out to us again or you may check out our self-help options located here: http://tpg.com.au/support