Facing connection refuse while connecting to Hadoop cluster

Facing below error while connecting to hadoop cluster from unix using hadoop fs command.

$ hadoop fs -ls

put: Call From cxln4.c.thelab-240901.internal/ to cxln1.c.thelab-240901.internal:8020 failed on connection exception: java.net.ConnectException: Connecti
on refused; For more details see: ConnectionRefused - HADOOP2 - Apache Software Foundation

Please help me resolve it