Here’s a tip I’ve been using for many years now.  To check connectivity from a disparate server to your database server, simply right-click on the desktop and select New, then select Text Document.  Name the file test.udl and hit enter.  Now simply double-click on the newly created .udl file and a dialog asking for connection information will appear.  Fill in the details and hit Test Connection.  Quick and dirty way to check connectivity problems.