Yep, ongoing issues with a large number of AU/NZ and OCE players.

Best guess at this time is that it is related to weather damage in Sydney (location of the datacenters) causing inconsistent routing. Using a VPN service can bypass the issue at the cost of latency.

NBN Co have made announcements about infrastructure damage in the area which would be a likely cause.

Would be nice to hear some confirmation from SE but I imagine this is mostly out of their control right now.