I can't even get this Brother to scan to a flash drive in its own USB port. It acts like it's successful; it scans and no errors show up... but the files just aren't there. Tried multiple USB drives and made sure they were formatted to FAT32 in a sector size that Brother recommended in the manual.

Printing to it from Debian was even easier than expected, though. Plug it in, it shows up as a networked printer, and you print to it.