Engine cut on/off feature. Always shows message Device is unavailable but vehicle is running.

Engine cut on/off feature not working. Always comes Device is unavailable. message.

Here is my code for sendCommandToDevice function

public static String sendCommandToDevice(Long deviceId, String postData) throws IOException{
        String response = "Message was not sent";
        //URL url = new URL("http://172.32.1.64:8082/api/commands/sendCommandToDevice/"+deviceId);
        URL url = new URL("http://ec2-13-127-235-172.ap-south-1.compute.amazonaws.com:8082/api/commands/sendCommandToDevice/"+deviceId);
        HttpURLConnection connection = (HttpURLConnection) url.openConnection();
        connection.setDoOutput(true);
        connection.setRequestMethod("POST");
        connection.setRequestProperty("Content-Type", "application/json");
        connection.setRequestProperty("Content-Length",  String.valueOf(postData.length()));
         
        // Write datasss
        OutputStream os = connection.getOutputStream();
        os.write(postData.getBytes());
         
        // Read response
        StringBuilder responseSB = new StringBuilder();
        //BufferedReader br = new BufferedReader(new InputStreamReader(connection.getInputStream()));
        BufferedReader br = new BufferedReader(new InputStreamReader(connection.getInputStream()));
          
        String line;
        while ( (line = br.readLine()) != null)
            responseSB.append(line);
                 
        // Close streams
        br.close();
        os.close(); 

        response = responseSB.toString();
        
        System.out.println("\n***********************************************************");
        System.out.println((new Date())+" CommandSent Response on =>"+deviceId+"<=: "+response);
        System.out.println("***********************************************************\n");
        
        if(response.contains("online")){
            response = "Device is not online";
        }
        if(response.contains("supported")){
            response = "Wrong command or Unsupported!";
        }
        
        return response;
    }

Please help me its urgent.