So I have this code

const express = require('express');
const Gun = require('gun');
const app = express()
const port = 3000

app.use(Gun.serve);

const server = app.listen(port, () => {
    console.log('DAPP listening at ', port)
})

Gun({ web: server });

I remember in ReactJS normal, I had a public with an index, and when I try to Custom server It was easy, but I move on to Next.js and I don't know how to Custom server this, also I'm using Gun.js so maybe that change a little bit:)