Elasticsearch Node not connectd

請問各位大佬有遇過這樣的問題嗎?
我有5個ES node  ES 版本為 7.1.0
其中 test-03 會出現 test-04 Node not connected  (下面第 一 個log)
        test-04 會出現 test-03 Node not connected  (下面第 二 個log)
兩個 log 差3分鐘而已。
但是cluster 並沒有異常，也沒出現 test-03 或 test-04 離開cluster 的問題，所以我不是很清楚問題點在哪裡。
如果發生 Node not connectd ，就我的認知應該會有node 離開cluster，但是卻沒有，不知道大佬們有沒有什麼想法可以提供，感謝!
 

[2020-05-07T15:39:03,470][WARN ][r.suppressed             ] [test-03] path: /customer*/_search, params: {index=customer*, filter_path=hits.hits._source}
org.elasticsearch.action.search.SearchPhaseExecutionException: 
at org.elasticsearch.action.search.AbstractSearchAsyncAction.onPhaseFailure(AbstractSearchAsyncAction.java:296) [elasticsearch-7.1.0.jar:7.1.0]
at org.elasticsearch.action.search.FetchSearchPhase$1.onFailure(FetchSearchPhase.java:91) [elasticsearch-7.1.0.jar:7.1.0]
at org.elasticsearch.common.util.concurrent.AbstractRunnable.run(AbstractRunnable.java:39) [elasticsearch-7.1.0.jar:7.1.0]
at org.elasticsearch.common.util.concurrent.TimedRunnable.doRun(TimedRunnable.java:41) [elasticsearch-7.1.0.jar:7.1.0]
at org.elasticsearch.common.util.concurrent.ThreadContext$ContextPreservingAbstractRunnable.doRun(ThreadContext.java:751) [elasticsearch-7.1.0.jar:7.1.0]
at org.elasticsearch.common.util.concurrent.AbstractRunnable.run(AbstractRunnable.java:37) [elasticsearch-7.1.0.jar:7.1.0]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128) [?:?]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628) [?:?]
at java.lang.Thread.run(Thread.java:835) [?:?]
Caused by: org.elasticsearch.transport.NodeNotConnectedException: [test-04][192.168.14.134:9300] Node not connected
 
 
 [2020-05-07T15:36:08,066][WARN ][o.e.a.b.TransportShardBulkAction] [test-04] [[mos-2020.05][0]] failed to perform indices:data/write/bulk[s] on replica [mos-2020.05][0], node[JHcEkr_jTKysIp3EZ0w6aQ], [R], s[STARTED], a[id=ee3jYDS2RiGWPcaIzbmaUQ]
org.elasticsearch.transport.NodeNotConnectedException: [test-03][192.168.14.133:9300] Node not connected