Welcome to TPG Community!
Based on an account located, the service has been affected by an unplanned maintenance yesterday but all has already been resolved now. We apologise for the inconvenience caused.
Should you still require assistance, please don't hesitate to let us know.
We apologise for the inconvenience this has caused you, @zhaoyang1011.
As per checking, NBN Co. has identified a fault on the network yesterday and has engaged field services to rectify the issue. They have replaced some network hardware and your service should be working now.
Feel free to drop us a message should you need any assistance. Thank you.