MyCloud: a NAS alternative to OneDrive

Or at least that was what I was hoping would happen

As far as I can tell, Excel files (and possibly others I haven’t discovered yet) cannot be edited live on mobile devices (the files are read-only). If downloaded, they can be edited, but they then need to be uploaded and the original file replaced by the (new) modified version.

It would also seem that simultaneous editing of collaborative documents cannot be achieved, the last file saved just overwrites previously edited files without warning.

Or am I missing something? - Please help.