What this means
The IEEE assigned the MA-L block 001893 to SHENZHEN PHOTON BROADBAND 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 00:18:93, it is SHENZHEN PHOTON BROADBAND TECHNOLOGY CO.,LTD hardware.