Which USB devices can I connect to the USB port on the front of my product?

See below.

External USB Device Specifications

Note: Use only external storage devices with independent AC power sources. External storage devices that are powered via USB are not recommended.

CD-R, DVD-R, and Blu-ray drives	CD-ROM/CD-R: 700MB DVD-ROM/DVD-R: 4.7GB (CD-RW, DVD-RW, DVD+R, DVD+RW and Blu-ray Discs are not supported)
Magneto-optical drive	1.3GB
Hard disk and USB flash drives	2TB Formatted in FAT, FAT32, or exFAT