Unable to send request to machine, but works on v1 app

Hi, I am new to fly.io and machines. My goal is to use machines to spin up a VM running a websocket server for an online game, with each game assigned to a unique machine. I am testing out machines now to get the basics working before I fully develop the WS server (I’m using Socket.IO). When I run fly deploy on my docker container, it works fine. However I want to use machines to be able to scale this app according to my needs. I am using the API in the machines docs. I have created a machine and it is running the same container. It also has an IPv4 address allocated. However, that IPv4 address does not work. It is the exact same config as the other instance that was deployed with flyctl. Why does the flyctl deployed machine work just fine, but this other machine not work? In other words, how can I direct my request to a specific machine through the allocated IP? Thanks!