Just check your web server where your hosted your app,
its seems like your web server is not able to access your database using connection information your provided to your connection string.
Some times, when database is located to different server and your web server is restricted over there to access or your database server and web server both are in different networks. your error message shows that your web server is not able to access your database, so please check your network connection and also check that your database is allowed to browser over network or not.
http://blogs.msdn.com/b/sqlblog/archive/2009/07/17/how-to-configure-sql-server-to-listen-on-different-ports-on-different-ip-addresses.aspx[
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