Title: Fail to Connect Data Source from Remote Machine
Keywords: SQL Server, Reporting Service, Report Builder, Connection, Data Source, Data Set, Remote Machine
If you can connection the db server from SSMS on a remote machine but get failure to connect data source when work on reports' dataset, that might be because in the connection string of the report data source, you're using a single dot "." or "(local)" for the Data Source segment.
The correct format is to use the db server name/ip with which you can connect the server from your SSMS.