I can get the Management Studio to connect to my named and default instances, even the report service and the profiler as well as the configuration tool work fine. But SSMA gives this: Connection to SQL Server failed.
A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: TCP Provider, error: 0 - No connection could be made because the target machine actively refused it.)

Why would the management studio connect but not the migration application?

Kevin

Hi Kevin,

Which SQL Server Migration Assistant (SSMA) tool are you using? As you want to migrate database to SQL Server 2014, please ensure that you are using SSMA v5.3 or later version.

Besides, do you connect to remote SQL Server instance from SSMA? If so, please check the following things. For more detailed troubleshooting steps, please review this blog.
1. Make sure you are able to ping the server where SQL Server is installed.
2. Ensure the SQL Server instance is enabled TCP/IP protocol in SQL Server Configuration Manager (SSCM) and it is listening on a valid TCP port.
3. If you connect to a named instance, make sure that the SQL Server Browser service is running.
4. Configure the Windows Firewall for the SQL Server TCP port and SQL Browser service if firewall is on.
5. Check out IPSec setting if you still face problem. See whether IPSec specification make dropping any packets.

There is also a similar article about how to connect to SQL Server from SSMA for your reference.
https://msdn.microsoft.com/en-us/library/hh313091%28v=sql.110%29.aspx?f=255&MSPPError=-2147217396

Thanks,
Lydia