Hi Bhargava
The first one is to determine the contectivity of the clients that are not able to access. Can they reach the IHS server? If not review your comunications or client comunications (if you can).
If yes then you need to review at the plugin side to know how is balancing the request to the cluster and try to determine why some clients can reach the application and others no.
Tell us WAS and IHS version (with FP) and OS to give better support.
Hope this helps. Tell us if you need more support.
regards