SQL Server: error when connecting

The application I开发者_如何学Go'm using tries to connect SQL Server named instance running on a dedicated database server. Here's the error I'm getting:

The TCP/IP connection to the host <instance_name>, port 1433 has failed. Error: Connection refused: connect. 

Is the firewall blocking my access or what? Should I dedicate a different port for this application?

The error refused connect implies that your connection does not have permissions to connect to this instance of SQL Server.

Are you using Windows Authentication or a SQL Server Login?

For troubleshooting guidelines see: Troubleshooting Server and Database Connection Problems