How to send a Disconnect-Request using java?

Question

I was able to send an Access-Request to Freeradius server and get Access-Accept, using tinyradius library in a spring boot application. Now I need to send a COA Request and then a Disconnect-Request to end the session.

I tried to send a COA-Request, and I get an error.

> 2019-07-23 08:11:26.383  INFO 1 --- [nio-8080-exec-2]
> org.tinyradius.util.RadiusClient         : communication failure,
> retry 1 2019-07-23 08:11:29.387  INFO 1 --- [nio-8080-exec-2]
> org.tinyradius.util.RadiusClient         : communication failure,
> retry 2 2019-07-23 08:11:32.391 ERROR 1 --- [nio-8080-exec-2]
> org.tinyradius.util.RadiusClient         : communication failure
> (timeout), no more retries

RadiusClient rc = new RadiusClient("172.17.0.2", "testing123");
CoaRequest coaRequest=new CoaRequest();
coaRequest.setAuthenticator(dto.getAuthenticator().getBytes());

RadiusPacket response = rc.communicate(coaRequest,3799);

I get 'Receive timed out' error and the request doesn't seem to hit the server either. I would like to know how to send the COA-Request and Disconnect-Request using Tinyradius library