Need Help with unexpected Reboots TVS-EC880

[pauldrt]

We have two TVS-EC880 Version 4.2.3 2017/02/13. In the past couple of months the first of the TVS-EC880 has rebooted unexpectedly twice.

NAS1 which has unexpectedly rebooted:
It has 2.99TB and has 2.13TB free
Running 8 x WDC WD20EFRX-68EUZN0 (SATA)
RAID Type: RAID 10 with a hot spare
Running 2 x Virtual machines
RAM Usage: 59% 1.4GB available of 6.0GB
Entware-ng 0.96 installed.
There has been no other errors in the log.

NAS2 hasn't rebooted.
It has 12.28TB and has 5.01TB free
Running 8 x WDC WD2001FFSX-68JNUN0 (SATA)
RAID Type: RAID 5
Running 3 x Virtual machines
RAM Usage: 39% 7.8GB available of 14.0GB
Entware-ng 0.96 installed.

Both NASs are in a controlled A/C room on a UPS using CE+T inverters.

There seems to have been other reports of the rebooting.
viewtopic.php?t=127078

Is there a know issue with this model?

The reboots are very frustrating as we use the unit as main file server and the VMs don't automatically restart after reboot.