kernel: Failed to contact local NSM - rpc error 5

[stormanger2003]

FreeNAS-11.1-U6.3 nfs share get throse errors:
Jan 9 23:33:52 localhost kernel: Failed to contact local NSM - rpc error 5
Jan 9 23:34:17 localhost kernel: Failed to contact local NSM - rpc error 5
Jan 9 23:34:17 localhost kernel: Failed to contact local NSM - rpc error 5
At that time, nfs shared folder will very slow and some time can not write data. and can not edit nfs-server at services.
I try some works follow this web: https://forums.freebsd.org/threads/failed-to-contact-local-nsm-rpc-error-5.16474/
But it not work.
How can I fix this errors? Please help~

 

[dlavigne]

Anything else in /var/log/messages when the error occurs? Google suggests that these errors tend to be due to faulty hardware or a faulty client (if the service restart doesn't resolve it).