Credentials for SQL Server data source in Power BI gateway

Hi,

 

I'm trying to create a data source for an enterprise gateway connecting to a SQL Server database. It keeps telling me that it's got an issue with my credentials and I'm not sure which credentials I should be using. I've tried for both Windows and Basic authentication. I've used my 365 account, my AD account (Not Azure) and an account I've created in SQL Management Studio with access to the database.

 

None of the documentation I can find on setting up a gateway addresses this. Can anyone give me a pointer?

 

Thanks,

 

Pete