1.Incorrect upgrade will damage your device.
2.Only firmware version V5.19.XX can be upgraded to this firmware.
3.Please upgrade your device by cable connection.
4.Do not power off the device when upgrading.
5.This firmware can solve the WAN Flooding problem and allows you clone the MAC address manually.
6.Please unzip the file you downloaded and use the file ended with "bin" or "trx" to upgrade your device.
7.After upgrading, please restore it to factory defaults and configure the device again.