Tl-wr840n V5 Firmware !NEW!
Joane Goes
Please upgrade firmware/software from the local TP-Link official website of the purchase location for your TP-Link device, otherwise it may cause upgrade failure or mistakes and be against the warranty.
Some official firmware of TP-Link products can be replaced by the third party firmware such as DD-WRT. TP-Link is not obligated to provide any maintenance or support for it, and does not guarantee the performance and stability of third party firmware. Damage to the product as a result of using third party firmware will void the product's warranty.
Hello all, this is a quite old thread, but I agree with @hijani that whenever you download and or upgrade the firmware on a TP-Link device, do remember to verify its country code and hardware version before upgrading, ensure you choose the correct firmware to install on your device.
Back to the initial question that some of you failed to upgrade the firmware on the TL-WR840N v4.0, I guess this is special and customized hardware that was developed for the local Service Providers, so you cannot install the generic firmware on it.