Truenas 13 NFS v4 client crashes QNAO.

When using Truenas 12 all my jails used v4 of NFS to connect to my Qnap via fstab. I did a fresh install of Truenas 13 and again used v4 of NFS within my jails to connect to Qnap.
192.168.178.20:/movies /mnt/myVol/iocage/jails/bazarr/root/mnt/movies nfs rw,intr,tcp,vers=4 0 0
After this. My qnap had every night an unexpected shutdown.
Server Name: SUPERNAS
IP Address:
Date/Time: 19-05-2022 02:48:12
Level: Warning
The system was not shut down properly last time.
Server Name: SUPERNAS
IP Address:
Date/Time: 20-05-2022 03:35:20
Level: Warning
The system was not shut down properly last time.
Server Name: SUPERNAS
IP Address:
Date/Time: 21-05-2022 02:29:29
Level: Warning
The system was not shut down properly last time.

Switching fstab to v3 solved this problem.