Internet access off the cloud

I have been reading the forums trying to determine how to make this connection. I want to have internet only in one room on the other side of the home. I have no attic access because the attic has been insulated with spray foam. I have a second wired cck, a pi and a broadband adaptor. I have located the cable run to the room. How do I set this up? Can I have two cck wired adaptors on the same network? My intention is to have a dedicated run to this room and stay off the cloud. Any help would be greatly appreciated.