Copying big files over WebDAV can time out

[rfc2822]

1. Put a big (in my case 40 GB) file into a WebDAV folder.
2. Access with DAVx5 over a file manager. In my case I have tried Ghost Commander, which seemed to work best. I have copied the file from the WebDAV share to the local device.
3. Notification appears, copying starts. Switch away to other apps and do other things.
4. After a few minutes, there is no progress anymore. If you switch back into the file manager, it says that copying failed.

How to work around the problem:

• Plug the device on power
• When copying has started, open DAVx5 (so that it is in foreground) and don't switch to other apps.
• (It doesn't matter if the display turns off.)
• 40 GB file transfer (Kiwix .zim file) worked without problem :)

I don't know which of the measures exactly works around the problem and what the exact problem is, but it looks like some background timeout. We should find that out and document / fix it.