You notice that the Windows Service (Connector) has errors on the dashboard and when looking in the logs you see these errors:
1/30/2014 8:39:44 PM: Failed to sync! Response: The underlying connection was closed: Could not establish trust relationship for the SSL/TLS secure channel.
This error is related to network connectivity to either https://api.opendns.com or OCSP (Online Certificate Status Protocol) validation.
Please, make sure port 443 TCP is opened and if you have specific rules allowing/denying access by IP addresses that all addresses related to ocsp.digicert.com are opened as well.