What this means
The IEEE assigned the MA-L block D814DF to TCL King Electrical Appliances (Huizhou) 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 D8:14:DF, it is TCL King Electrical Appliances (Huizhou) Co., Ltd hardware.