DHCP IP drop and Wifi drop (2.5 & 5 both) - Intermittent

Intermmitent DHCP / Wifi drop. 

- Model: c6300v2

- ISP - Cox

- Version : V1.03.04

Issue:

Multiple times a day , Dropps Wifi access to both 2.4 and 5G.

Checking wifi logs on the devices has no IP addresses (Indicates DHCP issue).

Sometimes, the SSID itself stop broadcasting.

The only step restores the connectivity is a reboot. 

Log shows alot of DDOS attacks.

Note: Tried rebooting and resetting device multiple times. No resolution so far. 

Suggestions?