what is your duration? And are you maxing out on any server resources?
600 Busy EverywhereAll possible destinations are busy. Unlike the 486 response, this response indicates the destination knows there are no alternative destinations (such as a voicemail server) able to accept the call.:§21.6.1
It would help to get some more details on your test and hardware setup. If you are running 9.0.x on a 4 core machine and running a heavy load tests, there is a non-zero chance you run into errors that are caused due to infrastructure limitations.
Note that starting in 9.0, server installer, by design reduces the number of server processes running on hardware that is below the recommended hardware for production use.While you can run the tests and learn something about that environment, the tool etc., it's really not a good idea for production / serious load use cases.
Please, tell us a bit more. would be great to see this working for more and more folks.
Thank you to everyone in the community who are trying this out and helping each other.
Product Manager - Tableau