What this means
The IEEE assigned the MA-L block 30C01B to Shenzhen Jingxun Software Telecommunication 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 30:C0:1B, it is Shenzhen Jingxun Software Telecommunication Technology Co.,Ltd hardware.