@GustavoTutty 

Hello Gustavo, so you know the communities focus is on the US Region and its customers.  We will try to provide best-effort support but for the best support you may want to post in the future on our global community at https://community.tp-link.com/en or for Spanish-based support you can try our Community for Mexico https://community.tp-link.com/mx.

The router's UI is by default unencrypted.  This is because it's not on the web.  It's a local access-only site so there really is no need to encrypt it.as you can only access it when physically connect to the router itself.  If you have your router connected to a TP-Link ID, that access is done through the cloud and is encrypted.  You can also enable SSH encryption on the UI in the Admin settings of your router. 

As for Advanced settings in Tether, there are some settings that are not available in Tether and need you to log into the UI to get to them.