That message gets logged when the node tries to respond back to the client but the driver has already given up waiting for the cluster to respond so the connection is no longer active.
It typically happens when running an expensive query and the coordinator is still waiting for the replicas to respond but the driver already reached the client-side timeout. It can also happen when the driver has been configured with a very low timeout value so the coordinator never gets a chance to respond back. Check for the timeouts configured on the driver. I'd also recommend reviewing the app queries for clues. Cheers! >
