we are running a cluster (ES v2.3.1) with two client nodes (namely C1,C2).
Production users send requests to C1 only while C2 is used for testing purposes only.
It happens very rarely that C1 is not responding to a request (we know for sure that C1 received the request but it is not replying). From the end-user point of view, the request remains pending (i.e., no timeouts are expiring nor exceptions appear on the ES side).
Is this possibly due to a bad interaction between C1 & C2?
Thanks in advance for your help.