Use wifi as the WAN port of a router? [closed]

How would you configure a router to use a wireless signal as their "WAN" port? Meaning, they don't bridge to the existing network but rather create their own private subnet.

Using Wifi-as-WAN is an odd setup, but is possible. Its availability is totally dependent on the router's firmware. It may also cause some limitations on using this router as a wireless access-path for client wireless devices.

Some Cradlepoint routers have this capacity, as described in the article Configure WiFi as WAN on Cradlepoint Routers.

I wish to emphasis that I'm not recommending here any product, just giving an example. I have never used or seen any Cradlepoint router in my life. Wifi-as-WAN does exist, but it's up to you to find your router.

As another example, see OpenWRT documentation for this type of setup.