mount.fs: protocol not supported.

Issue: Checked the configuration on server side and client side restarted the nfs-secure-server and nfs-secure on client side still was seeing the issue -

# rpcinfo -p   (run this on server side)

--> Showed proper support to NFS version 4

Solution:

Reboot the NFS server and ran "mount -a" on client side. Fixed it.

Tip: Just in case Check the fstab entry on the client side is correct.

Thanks!