WebDav drive in Windows 8.1 explorer - failing file transfer

Question

I mounted an external webdav-folder to a windows drive. Fine. But when copying or moving files to webdav --> system declines after the first file / or alltogether with messages like "file couldnt transfered" or "file ... to big for target system". Sometimes when trying to delete, it ist deleted but then error message pops up "file not found" (to delete i think).

To mount I start this:

net use Z: https://webdavspace.com /user:me pwd

Windows build: 6.3.9600

Sounds like sync of the system is not proper? Because: when using a client software to access webdav-provider, everythink works like a charme. Also changing the storage provider does not change anything.

Oh, also on an Android (There its a build in feature of "x-plore") I experience same problems but without "explaining messages" from the system.

Any idea, how to connect proper with windows and maybe android? I like it very much to exchange data between them this way.

Thanks a lot!