Error 100057 when transferring files

Hello. I just bought a PR4100 40TB, I had before a WD Mycloud Duo 16GB. I am trying to copy the contents of my Duo, to my new PR4100, over my network, just draging and droping big folders. every night I try to copy 1TB (or so) of files, but when I wake up I find error 100057 and can’t finish copying the files. How can i fix this error? Why is this happening? Is there a better way to copy my files to my new device? thank you. I am running it on a Mac Big Sur.