You indicated that you experience issues when using a Virtual Private Network (VPN) with your nbn® Sky Muster® satellite service.
Internet activity uses a system which acknowledges when data has been received before sending more.
Firstly, check and compare your service’s speed with and without a VPN over the nbn® network. This helps identify whether your slower speeds are due to the VPN connection, or if another factor is at play. To do this, perform a speed test using the following steps: