I don’t have these issues with the conductor app. It’s 100% stable for me. There’s a default action you can pick when adding a song to the queue. I usually have add to end. Then I go back after I’m done adding songs or just let the queue get there on its own. But it never disconnects for me. Very strange.
As to adding a network card, go under the assumption that it will be a competitor to a $1500-$2000 streamer…some but not all.