SMART connnect is giving this error.
Service Unavailable
The server is temporarily unable to service your request due to maintenance downtime or capacity problems. Please try again later.
This happens quite often on several servers
This happens to us as well, which we blame on the size of the CA (about 20 GB). Sometimes it seems that it comes back on its own (i.e., that it was general maintenance). Other times we fill our a form to submit a ticket with a service request.