iphone drops gsm and wifi with certain apps s.a. maps

Some apps where the iPhone drops gsm and wifi signal:

e.g. In google Maps, I want to download a map of my region by typing th command “ok maps” into the map's app search bar and tap search. Dowloading starts, but then the iPhone drops gsm and wifi signal before the download is complete, then the signals come on again after a couple of seconds.

e.g. in google+ idem drops gsm and wifi signal, which come on again after a couple of seconds.

How come and is there a solution?

Thy