Elasticsearch Nodes behind a load balancer

I setup a cluster of elasticsearch nodes on AWS. The cluster contains 3 nodes. The nodes are behind an ELB(Elastic Load balancer). The ELB has a DNS name say "a.b.c.com".

I am able to successfully run things like:

curl -XGET 'http://a.b.c.com:9200/_cat/nodes'

This proves that permissions and routes are working properly.

When I try to connect my Java Application server to Elasticsearch it fails with the following error:

org.elasticsearch.transport.ReceiveTimeoutTransportException: [][inet[http://a.b.c.com/172.31.27.110:9300]][cluster:monitor/nodes/info] request_id [57] timed out after [10000ms]
        at org.elasticsearch.transport.TransportService$TimeoutHandler.run(TransportService.java:366)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
        at java.lang.Thread.run(Thread.java:745)

This happens regardless whether I increase client.transport.ping_timeout.

The java code i use to connect looks as follows:

    Settings settings = ImmutableSettings.settingsBuilder().put("cluster.name", clusterName).put("client.transport.ping_timeout", 10000).build();
    client = new TransportClient(settings);
    TransportClient transportClient = (TransportClient)client;
    transportClient.addTransportAddress(new InetSocketTransportAddress(instance, esPort));

instance="a.b.c.com" esPort=9300(i tried 9200 as well)

Thx in advance for helping out.