@Lewis-Adams when you added the subdomain did you make sure to edit the url in config.json and on NGINX?
as @scottalanmiller mentioned this will be the main cause for the disconnection
logs give below error
heroku[router]: at=info method=GET path= "/socket.io/?EIO= 3&transport= polling&t=MPk3FXO" host=forum.host.in request_id=2e930357-1ffbfab-49179488a37c fwd="220.127.116.11" dyno=web.1 connect=1ms service=3ms status=403 bytes=185 protocol=http
First it was working fine. Then I added custom domain. Now it give this error.
Without custom domain, it works fine.
change domain url in loader js file fixed this
Don't change loader.js. Change your