I will be rebooting a number of servers to upgrade the kernels to a 4.18.0 kernel.  After the issues with NFS file locking caused severe operational problems with the client mail server today I decided to try the new 4.18.0 kernels on a few machines and it appears to be running significantly cleaner.  Several of the other Linux distributions we have available have already upgraded to 4.18.0 and we’ve experienced no NFS troubles on them.  Presently the web servers are now running 4.18.0.  Since that represents the heaviest load of all the servers and stresses the kernel the most, if it runs clean on the web servers it pretty much indicates it will likely run clean on everything else.