A Fixing nuxt SSR when the proxy do not pass over the complete URL path to your service.

nuxt.config.js

const buildTimeConfig = {
  base: process.env.APP_BASE_PATH || '/',
}

export default {
  env: {
    ...buildTimeConfig
  },
  serverMiddleware: [
    {
      prefix: false,
      route: '/',
      handler: (req, res, next) => {
        const regex = new RegExp(`^${buildTimeConfig.base}`)
        //
        if (!regex.test(req.url)) {
          const dest = req.url.replace(/^\//, buildTimeConfig.base)
          console.log('Rewrite', req.url, 'to', dest)
          req.url = dest
        }
        next()
      }
    }
  ],
  head: {
    titleTemplate: 'Project behind proxy',
    link: [
      { rel: 'icon', type: 'image/x-icon', href: 'favicon.ico' },
      {
        rel: 'stylesheet',
        href: `${buildTimeConfig.base}css/bootstrap.min.css`
      },
      {
        rel: 'stylesheet',
        href: 'https://stackpath.bootstrapcdn.com/font-awesome/4.7.0/css/font-awesome.min.css'
      },
    ]
  },
  static: {
    prefix: true,
  },
  build: {
    publicPath: `${buildTimeConfig.base}_nuxt/`
  },
  router: {
    base: buildTimeConfig.base
  },
  buildModules: ['@nuxt/typescript-build'],
}