Hey Sean6811,
Sorry to hear that your internet isn't performing as expected.
The first step I'd suggest is to check the status of telstra services in your area.
You can do this by visiting the Service Status page and entering your location.
If you can verify that the service status of your area is fine, I'd then proceed to contact support to ensure that your services on their end are working fine. If they're able to confirm that your connection should be fine, they will direct you to their technical support, who will be able to resolve any issues you may be having.
So once again, if you've confirmed the service status in your area, I'd proceed to using the 24x7 Live Chatservice and explaining your problems to them. They may even walk you through several steps to ensure your router is working correctly.
I hope you manage to get this resolved soon 