Ext3 Limitation

We have a CloudBerry backup job for a Ex2 Ultra, and we started having some issues with this job.
The following message:

An attempt was made to create more links on a file than the file system supports.

The CloudBerry answer was "Most likely your destination (\STORAGE\Cloud) has a limitation on the maximum number of folders in a folder. Does your NAS use ext3 filesystem? Ext3 has a limitation of about 32K subfolders in one folder.

The possible workaround is Upgrading NAS filesystem to ext4 (might require firmware upgrade). "
How can i upgrade the filesystem to ext4?

Best Regards,

The EX series uses ext4 file system natively. (I’m reasonably sure that ALL of WD’s current NASes do.)