Iphone Loses connection

My iphone 5 won't keep a connection to the wireless router. It will log on, connect and work on the internet connection, but if I leave the house and come back, it can't re-connect to the router, without rebooting the router every time. I was having the same issue with the wireless on Apple TV (it would connect, but if it turned off/sleep, I had to reboot the router to get it to connect), changing the DHCP loan time and the DHCP IP Address Range fixed the Apple TV, but the Iphone still isn't working