Why does Yandex disk freeze mounted on webdov?

Question

linux

It would seem the simplest thing, mounted a Yandex disk via webdov

https://webdav.yandex.ru   /mnt/yandex.disk   davfs   rw,users,_netdev    0   0

and basically everything works. Until the moment when you start uploading something
a couple of hundred megabytes, everything is normal.
After that
1. the filling stopped
2. dfit doesn't work
3. /mnt/(два раза таб)accordingly, too
4. in general, everything that at least somehow touches this directory
5 umount /mnt/yandex.disk- also hangs and is not going to hang down
Well, what could it be?
Well, and most importantly, how to unmount the disk?

centos 6-7
debian 9
mint same

Answer 1

and yandex webdav already "for a long time" does not work
small files, it still turns out sometimes
to upload now I tried the archive 12.4mb uploaded 11.6 and hung
up before calmly uploaded files up to 2GB