Good day @chalivendri,
Welcome to TPG Community!
Your NBN modem will provide you the error message since it will automatically configure itself to get the internet working. If the modem is not properly connected or if it can't detect any connection from the NBN network, it will provide you this message.
We were able to locate your account using your community details and found out that you were able to contact our Tech team.
After they've guided you on setting up the modem, we are glad that the internet was able to work.
Should you require further assistance, please let us know.