For customers experiencing any issues with their NBN service, we recommend the best thing to do first is check if there's an outage on the NBN network.
We have created this article that can guide you on How to Check for NBN Network Outage
If there are no known outages in your area, customers can proceed with the troubleshooting steps indicated on this link : https://www.tpg.com.au/support/nbn-hfc-cable/problems_connect_internet_nbn_hfc
In your case, your service was affected by an NBN network outage and was resolved by the attending technician by replacing the faulty hardware within the network.
Let us know if you need further assistance.