Posting this in case it happened to others.

I received this error today on both my PS4 and PC versions of FFXIV. Could not even bring up the launcher.

This seems to be a network issue and was solved by unplugging my modem/router, waiting about 30 seconds then plugging it back in to restore my network connection.

Was able to bring up the launcher and log in to FFXIV with no further issue.