Both the websocket server and the http server need to use the same app.listen() so that they can be ran on the same port.

Ok thanks et how i can do that on railway or in local please ? :)

Nothing to do with Railway, so unfortunately we won't be able to offer coding help here.

Ok i need to update my file server.ts on Strapi to do that ? How i can find my port in railway.app ?

export default ({ env }) => ({
  host: env('HOST', '0.0.0.0'),
  port: env.int('PORT', 1337),
  app: {
    keys: env.array('APP_KEYS'),
  },
  webhooks: {
    populateRelations: env.bool('WEBHOOKS_POPULATE_RELATIONS', false),
  },
});

You are already using the correct PORT environment variable for the http server, the websocket server needs to use the same http listener.

Ok thanks ! so i need to update my file to use the same http listener.

Sorry but the Strapi doc say : If you use websockets or Socket.io in your projects, the transfer command will fail. You will need to temporarily disable websockets or Socket.io or ensure that your websocket server is running on a different port than the Strapi server, or a on a specific route within Strapi to use the transfer command.

You need to run them on the same port because you can not expose multiple ports on Railway.

So i cant use Strapi transfer ?

If you are unable to have the http and websocket servers listen on the same port, you would not be able to use that feature.

can i temporarily disable websockets or Socket.io ?

That question would not pertain to Railway, as i've mentioned we unfortunately are not able to provide coding help.