Hi Paul,
Please share the logs regarding Adaptive processing server, Data Federation service error occurs mostly because of Adaptive Processing Tuning.
Please refer below KBA & Links
1694041 - How do you configure the Adaptive Processing Server (APS) for improved performance and scalability [Video]?
https://service.sap.com/sap/support/notes/1694041
Links:-
Best Practices for SAPBO BI 4.0 Adaptive Processing Servers
Thanks,
Daya