DS918+ 外置硬碟係唔係要特定型號?

想請教各位師兄,我試過插兩隻舊款1T USB2.0既2.5"外置落部機到,發覺係認唔到的,但插啲手指落去又認到,外置硬碟係唔係要特定型號?有無師兄用緊?唔該哂.