There are areas inside my house where my iPhone keep dropping the wi-fi connection, while my sister's iPhone 5 has no issue and holds the connection fine. I really don't wanna get the phone swapped at the apple store 'cos it took a few tries to find this exterior flawless one and it doesn't rattle excessively. I've already tried restoring as new - no difference. Can this be fixed by replacing the antenna? Or wi-fi adapter? Can the wi-fi adapters even be replaced? I can swap parts myself from a scrap iPhone 5. Thanks! Really appreciate any advice!