What this means
The IEEE assigned the MA-M block 8C5DB2D to Guandong Yuhang Automation 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 8C:5D:B2:D, it is Guandong Yuhang Automation Technology Co.,Ltd hardware.