Optus Sports - in my experience - is one of the best/worst generally at blocking VPNs, across all providers. I gave up in the end.
My hunch, is that they also check latency - basically anything over 150ms, is almost certainly outside of Oz … and that is even accounting for their generally sh*tty residential broadband connections over there.
My recommendation: think twice before even considering using service provided by Nord. You won’t have a constant experience with intermittent connectivity issues, unable to connect entirely at times… the paid for reviews on the review sites and app stores kinda say it all really.
Avoid like the plague… and that doesn’t even cover the auto-renewal issues people seem to be experiencing over and over.?!
OP I haven’t had any issues with any US service. Maybe try a smaller vpn. Surfshark for example or Proton. Why use Optus Sport? There are U.S. equivalents.
I have separate UK and USA residential IP VPNs - with different providers. Smaller is generally better, in my view.
I gave up on Optus, even tried all reasonably priced VPS - hosting in Oz is horrendously expensive generally and it would seem most VPN providers had already hosted there/got blocked (Optus, 10play, etc).