deploy on subpath domain

[bosznrt]

I have a google load balance point to https://domain.com/myapp as port 4000

then I have config next.config.js like it

module.exports = withBundleAnalyzer({
  assetPrefix: '/myapp',
})

but when I run next start -p 4000 the page can run html only but other such as _app.js or static file is not found

How can I fix it? I have already wasted a week.