*****  WARNING  *****

TP Link have begun locking firmware on their devices from late 2015.

You can expect that any device purchased after mid-2015 may have firmware

that prevents installation of third part firmware such as OpenWrt and its

derivatives such as VT SECN.


You are advised ***NOT*** to install SECN factory firmware on any device

unless you are certain that it will correctly install and operate OpenWrt

firmware.


If you install a generic OpenWrt firmware in place of the OEM firmware, 

then you can subsequently simply install VT SECN using the sysupgrade

firmware, but ensuring the systems settings are NOT saved when flashed.


On the LuCI Upgrade page there is a "Save Settings" check box that must be 

un-checked manually before proceeding with the upgrade.


On the command line, use the "- n" flage as follows:

    #  sysupgrade -v -n  <sysupgrade-file-name>