A network-related or instance-specific error occurred

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.

sql server,A network-related,instance-specific error occurred,The server was not found or was not accessible,Verify that the instance name is correct,SQL Server is configured to allow remote connections,