Connection Timeout Expired

We are having an issue resulting in the following Fatal Error message.

Connection Timeout Expired.  The timeout period elapsed while attempting to consume the pre-login handshake acknowlegement.  This could be because the pre-login handshake failed or the server was unable to respond back in time.....

Not sure the cause but we have a new server, Cat6 wiring, extended the timeout setting from 15 seconds to 30 seconds and made adjustments to the firewall.

Any suggestions that I can pass on to our IT Company, would be appreciated.