When you are using named instances for SQL Server, the TCP port for communication with the Database Engine will be different then the default SQL instance port: 1433. SQL Server will choose dynamic ports for each named instance. This is not very useful in firewall configurations. Therefore you can choose a static port for each SQL instance. If you want to use a static port, use the following procedure:
1. Open the SQL Server Configuration Manager (Start / Microsoft SQL Server 2008 R2 / Configuration Tools / SQL Server Configuration Manager)
2. Navigate to SQL Server Network Configuration / Protocols for [instance name] and open TCP/IP
3. Open the tab IP Addresses and navigate down to IPAll
4. Fill in the desired port at the TCP Port field
5. In order to take effect, the SQL Server (instance name) service will have to be restarted
The SQL Server Database Engine will now listen on the configured port.