In your Barn you want Internet? As your Barn is metal, cellular and wifi will not work. You have to use external antenna and put the antenna outside of your barn.

AR750s does not have detachable antennas. Maybe you can consider our X750 which you can use external antenna and work with wifi and cellular.

You may also try AR150-Ext, AR300M-Ext which has detachable antennas but only wifi, connecting to your home wifi.

In your barn, what devices do you need to connect to the Internet?