Thanks for raising this to our attention.
We've created an article that will guide you on How to check the connection speed on your NBN FTTN/FTTB service
If you've tested the speed using a WiFi connection, then signal interference may be causing the issue. Here are some articles that will help you improve your home WiFi network.
Here's another article to troubleshoot a Slow speed issue.
If you need further assistance, please send me a PM with your TPG username or customer ID number.