yarn 错误There appears to be trouble with your network connection. Retrying

yarn 错误There appears to be trouble with your network connection. Retrying…

原因：yarn超时

解决途径：
1、安装好后更换淘宝镜像

yarn config set registry https://registry.npm.taobao.org

yarn config delete proxy
npm config rm proxy
npm config rm https-proxy

npm 超时

安装cnpm镜像
npm install -g cnpm --registry=https://registry.npm.taobao.org
使用代理registry
npm config set registry https://registry.npm.taobao.org

遇到杂七杂八的错误，不要犹豫，node-modules删除，重新 npm install ,

注意：yarn install 和cnpm install 安装之后，如果启动报错，不妨试试 npm install