@Jeeptec 

If i disable the router portion in the Nighthawk and select modem only,  does this disable the ports too?

Yes, what will happen is the modem will give an internet connection to only one wired device to it, not mulitple. 

Would the M9 plus mesh system work fine without a double NAT error if i just disabled the wifi radios in the nighthawk so i could still use the lan ports

I've seen cases where the Deco will not be able to sync to the cloud because it is behind the firewall of the router it is connected to. Not always the case, but if you are able to set up the Deco fine while connected to your router, you can just disable the Wi-Fi.

lastly, If I make the M9 plus ssid the same as my existing wifi that i will be turning off, will all my devices hook up to it without having to re-setup all devices?

thanks in advance for replies

That should work fine, but some users have mentioned that not all devices automatically connected. What will probably need to be done in those cases is the saved network forgotten/deleted, then connected back so you are prompted to enter the wireless password again.

@Tony 

Thanks Tony, i think i will try and disable wifi first and see if it works, i can always go back in and disable router.....

If disabling wifi works, will it give me that double NAT ive been reading about?