My wife's iPhone 5 connects to our home Wifi only when it is very close to the router. If she moves 20 ft away the phone defaults to Verizon LTE. Both of our iPads and our laptop will connect everywhere in the house. It he iPhone 5 is in a case, but I took the case off with no difference in Wifi reception. Is this normal? I don't want to get hit with a huge overage data bill from Verizon.