This topic describes how to fix the issue if the Data Transmission Service (DTS) instance cannot connect to the source or destination database.
When you configure a data migration task or data synchronization task, both the source and destination databases pass the connectivity test. However, during the precheck, the message "The DTS instance cannot connect to the source or destination database" appears.
Configure whitelists for the source and destination databases. For more information, see Whitelist DTS IP ranges for your user-created database.