Hi @emilyzhang77 ,
We are aware of an issue impacting 4G services nationwide. Data services may be falling back to 3G intermittently, causing congestion and slower speeds for customers.
We are working to resolve this issue as soon as possible. We apologise for the inconvenience and thank customers for their patience.
You can visit this link for more details :https://www.tpg.com.au/servicestatus.php?category=35&timeframe=now