Welcome to TPG Community!
I've searched your account using your Community details and was able to find a match.
I did some test on your connection and it shows that too much upload which causing your slow speed issue.
Most of the time, cloud applications are causing high upload such as iCloud, Google Drive, One Drive, etc. It can also be caused by automatic system upgrade.
If you have multiple devices, you can try to leave one device connected to the internet one at a time until you figure out which device is causing the high upload traffic.
Nevertheless, if the issue persists even after isolating your devices, please let us know and we'll look into this for you further.
We'd like to check the status of the case that you've raised yesterday.
Is there any difference after doing an isolation of your devices?
Should you need further assistance, please let us know.
I can't properly perform an isolation test due to the fact I don't have an ethernet cable or any devices that can use them. However; I have recently discovered my modem-router (D-Link DSL-2880AL) is infamous for low speeds and poor connectivity. Could that be the problem?
It may be one of the possible reason for this issue.
However, I would highly recommend instead to speak with our of our Technicians to do further tests with you.
Let us know your best contact time and number via PM and we'll arrange a call for you.
For your reference, please see this How do I private message (PM) in the community.
You may wanna check this link for tips How to optimise your WIFI experience at home - https://www.nbnco.com.au/learn-about-the-nbn/in-home-optimisation.html ,Information on the link applies to every type of connection.
Hope this will help you as it did to me.
I've seen on the notes of our Technician that a Loan Modem has been requested it is currently pending.
I will advise them to call you again on Monday, once the Loan Modem has been approved.