In case of communication timeout with the server the client should log the connection details as the key will not give enough to analyse the issue.
It will be hard to know which connection/server is affected as the distribution will be based on the key's consistent hash algorithm and a user can not determine which server connection is used.

If that case the ERROR message should include the connection information as host-name or IP address AND port (to be unique for multiple servers with the same IP) to track that.
The access log can't be used in this case as there is no message because the server is not reached or already affected/blocked.

~~~

ERROR [stderr] (pool-12-thread-3) org.infinispan.client.hotrod.exceptions.TransportException:: java.net.SocketTimeoutException: GetOperation

{TestCache, key=[B0x800127656A6B2F6C..[103], flags=0} timed out after 60000 ms
ERROR [stderr] (pool-12-thread-3) at org.infinispan.client.hotrod.impl.Util.rewrap(Util.java:54)
ERROR [stderr] (pool-12-thread-3) at org.infinispan.client.hotrod.impl.Util.await(Util.java:27)
ERROR [stderr] (pool-12-thread-3) at org.infinispan.client.hotrod.impl.RemoteCacheImpl.get(RemoteCacheImpl.java:418)
...
ERROR [stderr] (pool-12-thread-3) Caused by: java.net.SocketTimeoutException: GetOperation{TestCache, key=[B0x800127656A6B2F6C..[103], flags=0}

timed out after 60000 ms
ERROR [stderr] (pool-12-thread-3) at org.infinispan.client.hotrod.impl.operations.HotRodOperation.run(HotRodOperation.java:172)
ERROR [stderr] (pool-12-thread-3) at io.netty.util.concurrent.PromiseTask$RunnableAdapter.call(PromiseTask.java:38)
ERROR [stderr] (pool-12-thread-3) at io.netty.util.concurrent.ScheduledFutureTask.run(ScheduledFutureTask.java:127)
ERROR [stderr] (pool-12-thread-3) at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:163)
ERROR [stderr] (pool-12-thread-3) at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:404)
ERROR [stderr] (pool-12-thread-3) at io.netty.channel.epoll.EpollEventLoop.run(EpollEventLoop.java:322)
ERROR [stderr] (pool-12-thread-3) at io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:884)
ERROR [stderr] (pool-12-thread-3) ... 3 more
~~~