Nighthawk X6 - Model R8000 no longer connecting to Internet

Hello! I purchased this router about 2 months ago and it was working fine until about 3 days ago. I am no longer able to get a wifi connection and receive an error message that it is not connected to the Internet.

I am unable to connect with my Mac (OS X Yosemite) nor any of our iPhone 6 nor our iPads. On our IMac, i checked under System Preferences, Network and for our WiFi, it shows it is ON and has a description stating "Wi-Fi has the self-assigned IP address 169.254.199.19 and will not be able to connect to the Internet".

I have tried rebooting our cable modem, router and desktop which has not helped any. I have also checked the cable modem & router -- both appear to be normal based on their lights -- the Internet connection is showing lit for bitb and they are both blinking as if data is moving between them.

I did a bit of research and noticed that my WiFi is configured for "Using DHCP" and the Condigure IPv6 is set to automatically. IPv4 Address is 168.254.199.19 with a subnet mask if 255.255.0.0 and the router does not have an IP address. I tried Remeejnd eve DHCP Lease several times and it did not solve the problem.

Not sure what to try next... any suggestions as I am clueless! Not sure why this set up stopped working all of a sudden when it was fine for the past 2 months -- we haven't made any changes nor updated our software recently.

Thanks!