DB Connection 실패시 나오는 에러 (방화벽이 차단했을경우등) SqlException (0x80131904)

방화벽이 차단했을 경우의 에러 메시지입니다.

결론, DB network접속이 실패 하는 경우입니다.

[Win32Exception (0x80004005): The network path was not found]

[SqlException (0x80131904): 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: Named Pipes Provider, error: 40 - Could not open a connection to SQL Server)]