I've got an AF-AF USB 3.0 adapter (the only thing I didn't have, and there were no USB2.0 available), installed USB Mode and tried to connect external HDD in boost mode.

Neither of two external HDDs work (wrote something about timeout), with neither cables I tried both on hdd side and on phone side.

Flash drives work all right, as well as Logitech wireless mouse.

Any suggestions? I can return the adapter to seller, should I?