I am working on creating a mesh network setup using the batman-adv routing protocol and a couple of Pis. One of my issues right now is turning one of those Pi nodes into a gateway node, which is connected to the outside internet. In order to do that, I use both the internal wifi adapter and an external USB adapter. However, the internal wifi adapter (wlan0) needs to be utilized by the batman-adv setup. How do I set up the Pi to therefore only utilize my external USB adapter to connect to the internet? Right now when I connect to a network through the Pi, it always defaults through the built in wifi card.