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.
In your case we've seen that that there has been a degradation to the sync speed of the modem/router, this can be solve by the following troubleshooting below.
On the other hand, we raised this to our Technical Team, expect them to contact you within 24-48hrs. Also, we'll have one of our Account Specialists to contact you separately to discuss upgrading your service to TPG-NBN.
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.