Can not connect to the server

I logged into my lap from my ad account (####\KavyaD) and login in to power bi using the same account. but due to a security concern, we have separate account to login into servers (####\KavyaDAU) . old server is ##.###.###.209 and recently bought a new server ##.###.###.6. i can go to remote desktop connection and log into the server and see the databases using ssms. and to access the server from local machine, i run the ssms by run as different user and use my KavyaDAU account to login. and i login to power bi using my ad account (KavyaD) and when i select get data and give the server ip address as ##.###.###.209, it connects. but when i add ##.###.###.6, it does not connect. gives an error saying " We encounted an error while trying to connect. Details: "Microsoft SQL: The target principal name is incorrect. Cannot generate SSPI context.". but it works for 209. then i tried login to ssms from my local machine by giving run as different user and gave credentials of my KavyaDAU account. that works for 209 but not works for 6. So there's a issue in server side not from power bi side. What should i do?