EnGenius ESR6650

Overview
"ESR6650-0.40 LFP" is silkscreened on the board in the FCC photos.

The device is an EnGenius ESR-9753 with a USB port (and minus two LAN ports).
 * Additionally, the FCC test report lists the ERB9250, ECB9300, Rosewill RNX-N4-3G, and HIFULL OBA-6800 as being identical models.

The device is on the DD-WRT supported devices table..
 * and is listed as having 4MB Flash and 32MB RAM.