Connect USB storage device to Huawei HG8546M ONT



I am not able to connect my USB hard disk to Huawei HG8546M ONT. When logged on to the HG8546M ont, I am trying to activate the ftp server the dropdown to select the usb device is not showing up. I tried couple of disks.

First one (1TB) with external power supply and another 160 GB without power supply.
The one with external power supply was able to bring the 'usb' light 'on' on the ont but the other one didnt even bring the light on. For both the drives none of them showed in the dropdown to be set as ftp server. I tried connecting the 1TB disk to laptop again but now its not getting recognized (dont remember when I was able to connect it). I have verified the 160GB hard disk and its FAT32.

Let me know if there are any pointers.