There has until now not been a freeze, during which I could not use SSH to reboot the device. So the device has never crashed on me 
Sure thing:
# rootfs is not mounted in fstab as we do it via initramfs. Uncomment for remount (slower boot)
#/dev/vero-nand/root / ext4 defaults,noatime 0 0
//192.168.1.101/movies /mnt/server-movies cifs x-systemd.automount,noauto,rw,iocharset=utf8,username=osmc,password=osmc,uid=osmc,gid=osmc,file_mode=0770,dir_mode=0770,vers=2.0 0 0
All the previous crashes have been with the above fstab, except that the mounts were configured with SMBv3 instead of v2 (vers=3.0). This morning I tried changing it to v2 instead, to see if it made any difference. It has not crashed since, but that could just as well be a coincidence.
My media is stored on a Windows 10 PC, on which I have added a dedicated user called “osmc” to access the shares, as a result of the SMB issue some time ago. I have been using this guide as a reference when setting up fstab: Configuring fstab based Samba share mounts