Hello   @CarimeBogni 

Range extender connects to Wi-Fi network of router and RE's web UI is protected by your router, the gateway or ' firewall' of the local network. 

We created a support email TKID220821902 so you could share more details with us,  please check your email inbox.  

It is also recommended to pay attention that if that's any of scam if anyone asks for the charge of the service. Kindly note that at TP-Link, we do not charge our customers for support services, the customer service is always free. And we have not authorized any third-party representative to install or remove the security files. 

To avoid any fraudulent, please check Notice of Fraudulent and non-TP-Link Affiliated Websites for more details. 

If anyone has similar security concerns, here is the correct channel to contact TP-Link technical support via Email/Hotline:  https://www.tp-link.com/support/contact-technical-support/