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_speed_nbn_hfc
Also, we've created some articles that will help you troubleshoot and improve your home network.
You may check these links:
In your case, we understand that you've contacted our Tech team and after resetting both NBN NTD box and TPG router, connection using the 5GHz improved to 46Mbps Down.
If you need further assistance, please let us know.