What's wrong with accessing ubuntu server via webdav?

Question

ubuntu

There is a server on Ubuntu and set up webdav access to it. Moreover, ubunta itself is on one disk, and access to files via webdav is on another disk, mounted. When I connect a network drive in Windows 7, the total size is shown one and a half times less than it actually is, although on the server, if you look, for example, through df -h, everything is fine. Mounted disk in NTFS, and in Windows it is visible as FAT. How to make it so that the normal size is visible? And is it worth formatting in ext4 for these purposes or is it normal in ntfs?