Help with networking

So, I'm trying to make a websocket backend using rust for a project I'm making. I'm really new to networking so I opted to use the simplest looking choice - message-io. My frontend is in Flutter, when I run the Flutter app the backend does recognize that a user connected, but when I send a message to the backend it doesn't seem to be recieved at the backend. In both programs I used the default example provided in the official tutorials, Work with WebSockets - Flutter (with the IP addresses changed to match each other of course). I assume it's because message-io requires specific formatting to work, but I don't know where to find what it should be if that's really the case.

I recognize that it might not be the best place to ask this, but I really don't know a better place..

I don't know what's wrong from this description. You could try to make a small example that shows the problem and post it to the message-io github issue tracker and ask for help there?