I upgraded to a Nexus 5 and still have issues with Opus hanging for long periods. I tested V11 in a VM, still just as bad.
I tried a few different Android FTP clients, but most of them don't support files over 4GB. To save everyone else time AndFTP does (play.google.com/store/apps/deta ... oft.andftp), although the interface is pretty clunky and it occasionally hangs. Wifi is of course quite slow, and you should always kill the client when not using it, for security reasons.