When connecting to a Tableau Server instance which uses an ECC certificate for external SSL, the following errors may occur:
In Tableau Desktop
Cannot connect to Tableau Server. Please check the server name and port and try again.
Error Code: 9F4C5638
Internet communication error: SSL peer certificate or SSH remote key was not OK (<server address>).
In Tableau Prep Builder
The required SSL certificate might be missing or doesn't match the Tableau Server certificate for "<server address>". Contact your System Administrator.