What this means
The IEEE assigned the MA-M block 18C3F4E to SHENZHEN MEGMEET ELECTRICAL 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 18:C3:F4:E, it is SHENZHEN MEGMEET ELECTRICAL CO., LTD hardware.