Can't move files directly from hardrive to Pr4100 copy button won't work!

So here is my deal just upgraded my storage to max out my bays and when uploading the data back onto the pr4100 the Copy button at the front usb will light up act like something’s there but it wont copy like its suppose to. I have been transferring files to a share folder linked to the pr4100 to get the files back on but the speeds are 11.9mbs and it bytes. So is there anyway to plug the hardrive directly into the usb’s on the pr4100 and do a drive to nas transfer without using the copy button? any suggestions would be awesome thanks allot!