Wifi strength weak suddenly

So this maybe because of me dropping my phone or may not be because of that.I'm not sure because the problems with the WiFi started the next day. So the Wifi works great when I'm next to it, but when I'm in the next door where the signal strength is great for other devices but my phone (Samsung galaxy core i8262) still shows weak strength. What should I do?

It's very annoying and Wifi keeps disconnecting and connecting back. I don't think there is any damage to the Wifi antenna.. Will a factory reset solve this problem?