regardless of whether the server is used for testing or not, a testing server must be set in the DW Site definition.
if yu are using the live server only, then it needs to be set as both the remote server and the testing server.
the error you are getting has nothing to do with the port, it has to do with the testing server settings in the site definition.
DW uses the testing server that is configured when it makes the database connection. If one is not set up and it is not properly set up, the database connection cannot be made.