What this means
The IEEE assigned the MA-M block 20B37F5 to Shenzhen HantangFengyun 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 20:B3:7F:5, it is Shenzhen HantangFengyun Technology Co.,Ltd hardware.