Widemac SL-R6801 (XDX-RN502H)

Overview
"XDX-RN502H V2.0" and "0921" is silkscreened on the board.

The manufacturer of this device appears to be widemac
 * Shenzhen Century Xinyang Technology Co., Ltd

Models product

 * N150 Routers • N300 Routers
 * Model No.: SL-R6801, SL-R6802, SL-R7201, SL-R7202, SL-R7203,
 * SL-R7204, SL-R7205, SL-R7206, SL-R7207, TK-R6801, TK-R7202,
 * SAI-BCS-104, SAI-BC-B209, SAI-SCS-103

Links of Interest

 * On the OpenWrt forums
 * 3G Router - RT3050F (XDX-RN502H V7.0)