I've installed tigertoolbox from Microsoft and I'm using SQL Server Performance Dashboard Report daily.
It's very useful and I suggest you to install it if you are not using it yet.
BTW, when I connect to localhost everything works smoothly but when I'm trying to connect to another SQL Server instance on the network I receive the error
An error has occurred during report processing. (rsProcessingAborted)
Cannot create a connection to data source 'DataSource1'. (rsErrorOpeningConnection)
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)
Access is denied
The answer is very easy: I can easily connect to localhost thanks to my credentials but I need to enter user/password for a remote SQL Server instance. How can I ask to SSRS to prompt user and password for remote SQL Server instance?
The problem Cannot create a connection to data source ‘DataSource1’. (rsErrorOpeningConnection) is even mentioned in the comments on the official Microsoft page but it's not mentioned how to fix this issue.
That is NOT the answer.
The error tells you that your server was not found, so it cannot be authentication error, the server is not reached so it just cannot authenticate you.
You should check your connection string if it's right. if it's correct, it can be firewall or your server is not configured to accept remote connections.
So for whe first thing post here your connection string, it looks like this:
My picture is for shared DSN, if you use it embedded you can find it in your report properties