Plug in error in Settings pages

I and new to Piwik and just installed Piwik on my website server and it seemed to be going well. However on Settings - Marketplace page or when trying to install a Plugin from the Plug in page I am getting the following error;

An error Occurred
curl_exec: Failed to connect to port 443: Timed out. Hostname requested was

Any suggestions?

Are you sure is reachable from your server?
What happens if you curl

thanks that pointed me the right direction. Our firewall blocks outbound traffic from the DMZ so once I temporarily opened it the error went away.