Re: "Failed to connect to BI Platform. If this error keep occuring then refer to SAP Note 1668437 for troubleshooting."

Have you checked the note it mentioned?

Basically this is a issue with the web service application URL config..

You should go to CMC > Application > webservice > properties and  and then make the access URL to  http://<WebServer>:8080/dswsbobje

And then restart the dashboard servers