Nothing happens after clicking "CONNECT!" button

• Write my moodle URL ( moodle.uns.edu.ar/moodle, as indicated by my admin )
• Click "CONNECT!" 

Then :

• an overlay showing "Loading" briefly displays,
• disappears,
• nothing else happens.

The app remains responsive, and I can keep pressing "CONNECT!", just to get the same behaviour. 

If at this point I press the "Back" button of my cell phone, the app goes into a window showing "Log in" at the top, and eternally shows "Loading". There seems to be one of these windows for each time I press "CONNECT!", but none of them never finishes loading. 

This is indeed a device specific question, since the app and server is working in other devices. 

Device: Huawei ALE-L23

Version: Android 5.0.1