This seems to be a recent change - and an absolutely ridiculous one.
Optus - this needs to be changed.
Solved! Solved: Go to Solution.
Optus only has the streaming rights in Australia, so they would most likely try to put in measures to reduce the chance of someone accessing out of Australia - and VPN is one of the major contributors of that.
Its quite common for video streaming services to be locked to a specific region and have measures against access from out of that region.
Which VPN Provide are you using? As @Logged-Off said, Optus IP restrict to Australia's IP ranges, you may need to contact your VPN provider and raise it them, the IP Address's they are using are not being identified as Australia, so Optus is blocking access to them. Geo Blocking is quite common, and lots of people use VPN's to access for example USA content in Australia. You could just disconnect the VPN when using Optus Sport, and re-connect when finished.
Private Internet Access. As I was saying, I'm connecting to an Australian IP address. So no, it's not to do with the VPN provider, it's to do with Optus blocking the Australian IP address of the VPN provider or some other means.
I could disconnect the VPN to watch Optus Sports, and that's how I've founded out they are blocking the Australian IP address range. But I don't really want to, as I should haven't to... hence the post.
PIA can also be used from connecting overseas to that VPN endpoint in Australia, so that would be why its blocked.
The following does mention using a VPN as a cause of an error:
You are not allowed to watch this video from your current location