Is there any way I can have my Wireless Router act as an extension of my non-wireless cable modem?

[Specineff]

I want to play my Xbox One and other games with no trouble, but my NAT is always strict, and thanks to my router, I think I have a double NAT problem.

I don't get these problems when I connect my modem directly to my computer or Xbox One, but the problem is that there's only one ethernet port and there's no wireless.

Is there any way I can have the router just act like a wireless enabler for the modem so I can connect things through wireless and ethernet and still use the exact same settings as the modem does?

 

[Beezy]

did you ever try logging into the router to change the NAT settings? turn of firewalls etc? or open ports of need be, the way your describing it is how the router was intended to be used, it extends the modems internet...

 

[Specineff]

I have a Westell 7500

The only NAT related things I see are Static NAT, and I turned the firewall off long ago, I also notice that my IP while routed is different from when I'm not