== Nanostation M5 ==
If you attempt to flash the extender and receive a 'Firmware check failed' error, then you have a version of the NSM5 that is protected from being flashed via the TFTP method. You will need to obtain a serial to USB interface (USB to UART TTL Module Serial Converter, 5 pin) and use it to flash the firmware.
Sending openwrt-ar71xx-generic-ubnt-nano-m-squashfs-factory.bin to 192.168.1.20 using tftp put
[Error: (Server) Firmware check failed]
=== USB to Serial Connection ===