Unable to do ftp file transfers between s PC and the device using Filezilla. Apparently, write access is inhibited in its file system. I’ve tried two different file managers, Mixplorer an Cx File Explorer, with permissions set appropriately and their ftp servers started. Curiously, I can look at the file system using an ADB shell with the LS command, and navigate through it as you would with any linux box, but unable to do push/pulls to transfer files. Had to use the back door (sneaker net with a USB thumb drive) to write my wallpaper jpg’s to the onn 4K Pro.