Sim router as a Wifi router?

I think I know what you are trying to do now.

A lot of things in IT work on the client and server model. Your PC when it connects to a wifi network is a wifi client, it takes from the wifi. A Wifi router, or Acess Point is a wifi server, it provides, or "serves" the connection.

You are asking, can your router act as a client and as a server, e.g. connect to a wifi network and share it to other clients. Short answer is no. Very few consumer type routers can.

I know its nonsensical, as all the technology is there, but it takes a very different software configuration to enable it, and 99% of clientele don't or won't need that functionality so it gets dropped.

The quickest solution for you is to get a wireless to ethernet bridge. The bridge acts as a wifi client and connects to a wifi network near you, and shares the network via ethernet, which you can then plug into your existing router.