Netgear R7000P w/ DD-WRT v3.0-r30776 Losing Connection

I have Comcast Xfinity and Netgear C6250 gateway with "Router Mode" off acting as my modem. I'm using a R7000P with DD-WRT as my router. At least once I day, I randomly lose my internet connection. WIFI connection is still solid and the router still shows a WAN IP address, but it loses connection. Only way I can re-establish connection is to reboot router. Any thoughts on how to resolve this?