This has now been resolved

We believe we have root caused the issue to one of our server providers updating their data center networking infrastructure, which appears to have increased instability. They have reverted the changes and we are now monitoring to ensure this fixes the issues experienced.

We're observing intermittent timeouts when starting stream outputs. We're looking into the root cause and will update as we find out more. If you're experiencing this issue then wait a few minutes and try again. The issue does not seem to be affecting already running streams.