Good signal/bars but no network connection many times daily

4 years after the original post, I'll go ahead and add that me and my mother have the same phones A32's, are on the same account and live next door to each other. Her phone is constantly going into no signal mode. The tiny bars icon that you need a magnifying glass to see and then an hour to find out what it means, has an X on it and no bars. She has a wifi connection from her ISP and therfore can surf the web and of course thinks everything must be fine. However she never gets txt messages or phone calls because she has no mobile data coming in. Have tried everything suggested here. The only thing that helps is a reboot. Then all the important txt messages come pouring in. You shouldn't have to reboot your phone every 30 mins in order to do the one thing a phone is supposed to do with absolutely everything else secondary. Aggravating to say the least.