在使用webpack 3.8的react路由器4.2中刷新后无法获取/aboutus页面

import React from 'react';
import { BrowserRouter as Router, Route, Switch } from 'react-router-dom';

import Home from './components/Home';
import AboutUs from './components/AboutUs';

const App = () => {
  return (
    <Router>
      <Switch>
        <Route exact path="/" component={Home} />
        <Route path="/aboutus" component={AboutUs} />
      </Switch>
    </Router>
  );
};

export default App;

const express = require('express');
const path = require('path');

const app = express();

// 静态文件服务
app.use(express.static(path.join(__dirname, 'build')));

// 所有路由都返回index.html
app.get('*', (req, res) => {
  res.sendFile(path.join(__dirname, 'build', 'index.html'));
});

// 启动服务器
app.listen(3000, () => {
  console.log('服务器已启动');
});

module.exports = {
  // ...
  devServer: {
    historyApiFallback: true,
  },
  // ...
};