It’s telling you that it can’t connect to the CMS.
That might be because the URL you’re using is wrong, or it might be because a firewall is blocking your access.
If you open the web browser on your Android device and enter that same URL, do you get the CMS login page shown?
If not, you need to investigate why that isn’t possible.
no i didn’t get on the browser 
can you tell me the causes of this problem or the conditions to respect for the correct operation?
I have already explained. The URL you’ve entered is either wrong, or, there’s a firewall blocking you accessing the webserver is that URL is correct.