Agent went offline during the build

Jenkins agents going off-line with the following error during build.

Agent went offline during the build
Build step ‘Execute shell’ marked build as failure
FATAL: Remote call on JNLP4-connect connection from 100.122.0.2/100.122.0.2:47648 failed. The channel is closing down or has closed down
java.nio.channels.ClosedChannelException
at org.jenkinsci.remoting.protocol.NetworkLayer.onRecvClosed(NetworkLayer.java:154)
at org.jenkinsci.remoting.protocol.impl.NIONetworkLayer.ready(NIONetworkLayer.java:142)
at org.jenkinsci.remoting.protocol.IOHub$OnReady.run(IOHub.java:721)
at jenkins.util.ContextResettingExecutorService$1.run(ContextResettingExecutorService.java:28)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
Caused: hudson.remoting.ChannelClosedException: Remote call on JNLP4-connect connection from 100.122.0.2/100.122.0.2:47648 failed. The channel is closing down or has closed down
at hudson.remoting.Channel.call(Channel.java:901)
at hudson.Launcher$RemoteLauncher.kill(Launcher.java:1079)
at hudson.model.AbstractBuild$AbstractBuildExecution.run(AbstractBuild.java:510)
at hudson.model.Run.execute(Run.java:1724)
at hudson.model.FreeStyleBuild.run(FreeStyleBuild.java:43)
at hudson.model.ResourceController.execute(ResourceController.java:97)
at hudson.model.Executor.run(Executor.java:421)
Finished: FAILURE

currently enough space and commute to proceed with the build and the controllers version matching with the agents.

does this happen every time? or it happened once?

If its once, just retry, its possibly just a network issue.
If every time, take a look at the logs for the agent