I have been copying files to an ext3 formatted external drive for some time without issue but today i am unable to copy, i see error: “Failed to copy file(s)”
Hard to know what to do next unless you install the Custom Firmware. This should let you copy the files directly to a PC (any FS supported on the PC- eg NTFS).
The basic setup details are in the download. The detailed ones for the multiple options are in the documentation you get when the full interface is downloaded on first log on to the local IPaddress of the box using the browser of your choice.