https://blog.wongcw.com/2020/09/17/apple-watch-series-6%e6%94%af%e6%8c%815ghz-wi-fi%e5%b8%b6%e4%be%86%e6%9b%b4%e7%a9%a9%e5%ae%9a%e7%9a%84%e9%80%a3%e6%8e%a5/