undertow webserver not binding to remote address

I'm testing out the undertow 2.0.0.Alpha1 webserver. When I run it locally it works and returns Hello World when I go to localhost:80. I then deploy the webserver on a remote server and go to remote_ip:80 but I get no response back. If I run curl -i -X GET http://localhost:80 on the remote server then I get Hello World back as well. So the server is definitely running but for some reason it's just not accessible via the remote ip address. If I try to set a hostname as the remote IP in the code (i.e. .addHttpListener(80, "remote.ip")) then I get a BindException.

import io.undertow.Undertow;
import io.undertow.server.HttpHandler;
import io.undertow.server.HttpServerExchange;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;

public class HelloWorldServer {

    public static void main(final String[] args) {
        try {
            Runtime.getRuntime().exec("sudo fuser -k 80/tcp");
        } catch (IOException ex) {
            Logger.getLogger(HelloWorldServer.class.getName()).log(Level.SEVERE, null, ex);
        }
        Undertow server = Undertow.builder()
                .addHttpListener(80, null)
                .setHandler(new HttpHandler() {
                    @Override
                    public void handleRequest(final HttpServerExchange exchange) throws Exception {
                        exchange.getResponseSender().send("Hello World");
                    }
                }).build();
        server.start();
    }

}

Any clues?