Wi-Fi won't reach my room anymore?

We have one router in the living room and I have to sit out there next to it to use Wi-Fi, it used to work in my room just fine but just stopped. My sis room is right next to mine and hers works fine. It's only my pos iphone that doesn't connect. What can I do? (We have xfinity/comcas )

Why doesn't my iphone 5 connect to my wireless internet at home?

Like it does when i go closr to it, but after like 15 minutes it stops and disconnects. Why does this happen? My ipod works very good and doesn't even do this, even when i go somewhere far away (at home) it still works. But my phone when i go to my room it doesn't even work. Please tell me what to do?