We are still currently holding a router provided by TPG which is the TP-Link Archer C1200 with the ff details:
Firmware Version: 1.0.0 Build 20180208 rel.59779 (EU)
Hardware Version: Archer C1200 v1.0
Our connection is already switched to another provider Dodo, but our TPG account is still running for this month. And in the router basic setting under internet tab, the username password still indicated there is our TPG account. Is there anyway this router be updated?
You can use the TPG modem given that you configured it with your current Telco's authentication details and if it is compatible with your current NBN technology. Although, you will not be able to use the VoIP function.
Let's check whether your account is still active by sending your TPG account details via PM.