Unable to execute CURL command on Schema Registry REST API

I’ve 3 instances of Schema Registry up and running on a unix server with specific port numbers specified corresponding to the listener parameter in each of the schema-registry.properties file. When I try to trigger the API using CURL command on the server, it fails returning Failed to connect connection refused. The below is the simple CURL command which I’m trying to execute.

  1. curl -X GET http://localhost:PORT_NUMBER/subjects
  2. curl -X GET http://HOST_NAME:PORT_NUMBER/subjects

Can anyone help me with this issue?