Your topology? Is this helpful? http://www.tp-link.com/en/article/?faqid=560

:) Your guys can submit your suggestions for evaluation here. http://www.tp-link.com/en/Support/contact/

Obviously, TP-LINK people misunderstood what security you are talking about. As stated, TP-LINK engineers have checked its product portfolios and the result is that TP-LINK wireless router, ADSL...

Try channel width 40MHz on the router and ensure the network is secured with WPA2-PSK, AES.

Is it TL-WDR6500? That is a Chinese product. If you don't understand Chinese, why you buy it? Email to fae@tp-link.com.cn for technical support.

On the device itself, there is Wirless ON/OFF button, right? If you turn it off, Wi-Fi function will be disabled.