The issue is caused by an issue in the SQL DataSource Wizard that doesn't provide the correct Data Provider name. In the wizard on the first page, the Data Provider must be MySql.Data.MySqlClient, but the option is limited only to MySql.Data. Since the engine cannot determine the type of the data provider by that name, it falls back to System.Data.SqlClient and claims that "Port" is not a supported keyword.

The workaround is to avoid using the SQL DataSource wizard and edit the data source properties directly in the properties grid. You can check the attached silent video that demonstrates how to do so.