Okay, so my brother had an old iPhone 4 that was broken (screen cracked, home & lock button don't work, etc). He got it fixed for $140 and gave it to me and now its working brand new. However there's one problem. My iPhone can't find any wi-fi unless it is close to the router. For example, the router to my house is in my room, I can only use my internet's wi-fi on my phone in that area, I can't use it in my living or in my sister's room or in the kitchen. It's the same everywhere else. I have to be near the router to access wi-fi otherwise my phone goes to 3G internet. I don't ALWAYS want to use 3G because it wastes my data plan. Please someone help me. There has to be a reason for this. It will mean a lot.
Thank you.
P.S It's an iPhone 4, White, 16GB with iOS 6.1.3