File Transfer Optimum Speed

I have a 3tb WD drive attached to my WD My Cloud, I’m trying to transfer 4gb files to the external drive that is attached to the My Cloud through my network. What is the best way to transfer these files with optimum speed?

Since you are trying to copy data to the external drive attached to the My Cloud, I would think, the easiest way, without having to do ssh stuff, would be to disconnect the drive from the My Cloud temporarily, and attach it to the computer that has the 4 gigs of files…but then again 4GB is really not that much data and if the computer that has the 4GB data is connected to the network via a wired connection, you can just do it directly from the computer straight to the network share via Windows explorer.