What this means
The IEEE assigned the MA-M block 4048FDA to Shenzhen Yifang Digital 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 40:48:FD:A, it is Shenzhen Yifang Digital Technology Co., LTD. hardware.