Welcome to the community!
There are different cause of Transfer/Speed Issue that you may experience.
In the event that you experience dropouts via Wireless/Wi-Fi connection we did an article that you may find helpful see links below.
We have created this article that can guide you on How to Check for NBN Network Outage.
Should you need further assistance, feel free to search community for help or chat with us at https://www.tpg.com.au/support/contact/ and we'd be glad to assist you.