Re: server NFS not responding, still trying

What version of RedHat? This KB might apply to you.

https://kb.netapp.com/Advice_and_Troubleshooting/Data_Storage_Software/ONTAP_OS/Intermittently_receiving_%22NFS_not_responding%22_errors_on_the_unix_client

Does the event log contain any messages relating to NFS or anything around that time period you observed the issue? 

Run and share the below output from cluster shell

>> event log show -message-name *nfs*