Recently I am not able to upload large files (movies, tar-archives > 1GB) to my cloud storage service using my network folder in Dolphin. Small files (text files, images documents), however, are uploading fine.

The network folder is cloud storage from Stack (by TransIP), which is functioning properly.
This is my connection address used in Dolphin: webdav://myUserName.stackstorage.com:80 ... php/webdav
Webdav is the only supported protocol when using Stack as far as I know.
I have all the right permissions, meening that I can create, read, modify, execute and download all my files and folders.
There is no difference in moving or copying the files.
I have tried modifying my php.ini file, settings like 'upload_max_filesize'.
When running Dolphin from the command line in order to check the output of the error, it gives none.
I am running Dolphin version 17.04.3 on KDE Plasma with Arch Linux Kernel: x86_64 Linux 4.12.3-1-ARCH

Two screnshots in regard of this error are below,
http://imgur.com/a/AgB8J

At this point I am out of ideas on what I can do to resolve this issue.
Any tips or pointers in the right direction are greatly appreciated.