Hi Luca,
I am trying to understand the situation here. It sounds like your WiFi connection is unstable.
Is your WiFi router far way from the Netro devices and is it possible the WiFi signal is not good enough? How many signal bars on your phone at that location?
I can see your second device is connected and there is no reason why the first one could not unless the WiFi signal is an issue. For testing purpose if you move the first Netro controller closer to the router, will the connection be stable?
If you are sure the WiFi signal is strong please let us know and we will need to look at something else.
Thanks,
Netro Inc