Error when trying to move datadir to Freenas CIFS or NFS share

I have NextCloud Plus installed on a Rock64 4GB board, but have not yet logged into to the user web interface or attempted to upload any data.

I want to use a mount at /media/nextcloud as the data directory. I have a CIFS share configured on a separate Freenas server. I’m able to mount the share from a command line, and have /etc/fstab configured to mount the share using this line (I know I need to move to a credentials file once this is debugged:

// /media/nextcloud cifs defaults,rw,username=xxxxxxxxxx,password=xxxxxxxx,domain=WORKGROUP,uid=www-data,gid=www-data,,auto,user

The share appears with user and group of www-data:www-data. I’m also able to mount the share from an Ubuntu workstation on the same network.

Whenever I try to move the datadir to the share, I get the message “Only ext/btrfs filesystems can hold the data directory”

The data volume on the freenas server is ZFS, but I don’t think that’s relevant in this case.

I’ve tried changing to different user:groups, CIFS and NFS shares, setting permissions and changing the permission types (windows, unix) on the shared volume with no change.

Can anyone give an example of mounting a CIFS or SMB share for a nextcloud data (and/or database directory) with mount/fstab entries and what appropriate permissions are.