public async Task ChangeListenerTargets(string listenerArn, string targetGroupArn) { var requestGet = new DescribeListenersRequest() { ListenerArns = new List <string>() { listenerArn } }; var responseGet = await client.DescribeListenersAsync(requestGet); Listener listener = responseGet.Listeners[0]; listener.DefaultActions[0].TargetGroupArn = targetGroupArn; var request = new ModifyListenerRequest() { ListenerArn = listenerArn, DefaultActions = listener.DefaultActions }; await client.ModifyListenerAsync(request); }