On Tue, May 07, 2019 at 03:00:54PM +0000, James Pearson wrote:
We have a number of identical NFS clients mounting a server using NFSv4.1 - server and clients are all running CentOS 7.5 (kernel 3.10.0-862.14.4.el7.x86_64)
Have you updated to the supported CentOS7 kernel and NFS utilities? There have been dozens of updates to the NFS code in the kernel since the kernel you're running.