What this means
The IEEE assigned the MA-L block 28AD3E to Shenzhen TONG BO WEI 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 28:AD:3E, it is Shenzhen TONG BO WEI Technology CO.,LTD hardware.