What this means
The IEEE assigned the MA-L block 2C3731 to SHENZHEN YIFANG DIGITAL TECHNOLOGY CO.,LTD.. Every network interface they manufacture under this block has a MAC address beginning with these digits, followed by a unique per-device identifier. If a device on your network shows a MAC starting 2C:37:31, it is SHENZHEN YIFANG DIGITAL TECHNOLOGY CO.,LTD. hardware.