https://blog.wongcw.com/2019/07/04/%e9%9b%99%e9%a0%bb%e8%b7%af%e7%94%b1%e5%b0%b1%e5%88%a5%e5%86%8d%e7%94%a82-4ghz-wi-fi%e4%ba%86%ef%bc%9a%e5%af%a6%e6%b8%ac5g%e9%a0%bb%e6%ae%b5%e7%a9%bf%e7%89%86%e5%92%8c%e8%a6%86%e8%93%8b%e6%80%a7/