I have been playing with an Android tablet and dongle and have run into something I don't understand (nothing new there). I have a wi-fi device right next to the desk and the Android devices and a Windows laptop all report the signal as strong. Yet the Android devices keep dropping the connection at odd moments. Usually it comes on again just afterwards, but this afternoon it refused to connect for a half-hour and nothing I tried (reset, power off and on) would get it to work. It showed the wi-fi signal as maximum strength and secured, but it wouldn't connect regardless of how many times I tapped on the button. Finally, it did connect while I was doing something else and everything worked fine again.

I have very limited Android experience and don't understand what is going on here. What prevents Android from connecting to a wi-fi signal that is strong and persistent? Why does the connection keep getting dropped? What am I missing?

Maybe I should add that there are few sources of interference nearby, just some computers and a landline wireless phone. We live in the countryside, away from transmission towers and competing wi-fi signals or electric fences.