Error when setting up credentials for on prem report server

[mart1fio]

I have a report I have created in PBI Desktop from a SQL server database. I can connect to the server from PBI desktop and can enter the sql query details in the advanced box. I have published this report successfully to our on prem report server. I then went to set up an auto refresh for this report. When I typed in my credetials and tested, this is the error I got;

Microsoft SQL: 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. (provider: Named Pipes Provider, error: 40 - Could not open a connection to SQL Server)

The server has been configured correctly for remote connection so that isn't the issue. I can open the report in PBI Desktop, refresh it and then save with no problems. Could this be a server configuration issue or potentially a firewall issue between our Report Server and the SQL Server? I don't have this issue with any of the other databases I use on different servers in our network. 

[mart1fio]

THe report was created in PBI Desktop then published to the Onprem PBI Report Server. THe problem is sitting with the Report Server side as PBI Desktop is able to connect to the database every time I click on refresh from it.

[vk_pbi]

Did you used the Power BI Desktop or Power BI Desktop RS (Report Server) tool. I observed that, RS version special designed for Report server. Secondly, are you using Onprem Server or Power BI Service to distribute your reports ?