Phone constant disconnects from wifi

Some tips for improving WiFi performance;

http://corporate.comcast.com/comcast-voices/10-ways-you-might-be-killing-your-home-wi-fi-signal

http://forums.xfinity.com/t5/Your-Home-Network/Improve-Your-Wireless-Gateway-Home-Network/td-p/2627659

https://www.xfinity.com/support/articles/improve-your-wireless-home-network

There are other options. Google for WiFi repeaters / range extenders, WiFi mesh systems / pods.