Unable to connect to Oracle Autonomous database Database version: 21c

I am trying to use DB Connector as well as Oracle Connector (after installation/configuration).

I am getting an error - Execute failed: ORA-17002: I/O error: Connection reset, connect lapse 9 ms., Authentication lapse 0 ms for both cases.

I have tried both ojdbc8.jar as well as ojdbc11.jar.