It looks like the error is from SessionBuilder class. The google said that it might be a server-related issue and require a modification on hosts. But I’m not sure.
As far as I know, cURL is all setup correctly on our end.
But some other posts, including the GitHub issue @jaikrishna.t linked to all say that this is a DNS issue. Perhaps the domain name is invalid or blocked on our end.
Which hostname are you trying to connect to from your code?
In that case, it may be a consequence of using Guzzle Async. I don’t know exactly how Guzzle achieves the Async capabilities, but it might be that some of the restrictions we have on PHP execution for security and performance may be preventing Guzzle Async from working correctly.
In that case, you should still be able to use Guzzle, but only in the regular synchronous mode.