Payment Completion by VISA being blocked/errored with HTTP 503

[gvoice2006]

Per the following access logs, I see that the POST by VISA to complete the payment process is failing with an HTTP 503 error. None of us can figure out why this is happening. Does anyone here have any ideas?

198.241.206.38 - - [02/Jul/2017:00:29:55 -0400] "POST /wc-api/WC_Tech_Autho HTTP/1.1" 503 2903 "-" "-"

[RichardH]

Hello @gvoice2006

Is this for your sandbox or production account?  Are you using our API or an SDK?  Please also note that the sandbox now requires a TLS 1.2 connection.

Richard