Network Error Transferring large number of files

I am transferring all my videos, photos and music to my 4TB MYCloud drive.  When I grab one of the folders, ie, Video, and drag it to the drive, files begin to copy over.  I am getting a network error every 3 to 15 minutes.  I can only get past the error by clicking “Skip”, then it continues on.  When I do this, the current video I was transferring is removed from the Cloud drive.  I can select that one video, drag it over and it will successfully copy.  This also happens when doing photos or music, so I have not transferred any of that as I have way too many files there to try and ensure that all files are copied over.  Does anyone have an idea how I can fix this?  Is this a router issue?  Is this a file issue?  I am hooked up wired to the router to my devices.

When i move a big amount of files from a  source to a target i prefer to copy and after that delete them from source.

Cause you don’t specify your OS i will use a free tool like Freefilesync (linux,mac,win) to synchronize files (very fast and reliable) using update mode.

Left panel is source right panel is target.

After the operation has finished you can delete source files if you want.