What this means
The IEEE assigned the MA-M block 84B386D to Dongguan Amsamotion 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 84:B3:86:D, it is Dongguan Amsamotion Automation Technology Co., Ltd hardware.