问题产生：无论是vs2019还是2017，都有可能存在进度条0%不动。
问题说明以及解决方案：
1、此问题和是否使用科/学上网并没有关系，不用骂绿/坝。
2、在你的电脑里：用户/AppData/Temp下找到你进度条不动的时候的日志打开它，你会找到一个堆栈报错日志如下：
VisualStudio Bootstrapper:2021/1/14 6:11:00: Beginning file download. File = https://aka.ms/vs/16/release/installer.
VisualStudio Bootstrapper:2021/1/14 6:11:00: Download requested: https://aka.ms/vs/16/release/installer
VisualStudio Bootstrapper:2021/1/14 6:11:00: Attempting download 'https://aka.ms/vs/16/release/installer' using engine 'WebClient'
VisualStudio Bootstrapper:2021/1/14 6:11:04: WebClient error 'ConnectFailure' - proxy setting 'Default' - 'https://aka.ms/vs/16/release/installer'.
VisualStudio Bootstrapper:2021/1/14 6:11:08: WebClient error 'ConnectFailure' - proxy setting 'DefaultCredentialsOrNoAutoProxy' - 'https://aka.ms/vs/16/release/installer'.
VisualStudio Bootstrapper:2021/1/14 6:11:12: WebClient error 'ConnectFailure' - proxy setting 'NetworkCredentials' - 'https://aka.ms/vs/16/release/installer'.
VisualStudio Bootstrapper:2021/1/14 6:11:16: WebClient error 'ConnectFailure' - proxy setting 'DirectAccess' - 'https://aka.ms/vs/16/release/installer'.
VisualStudio Bootstrapper:2021/1/14 6:11:16: WebClient failed in 'https://aka.ms/vs/16/release/installer' with '无法连接到远程服务器' - 'https://aka.ms/vs/16/release/installer'.
VisualStudio Bootstrapper:2021/1/14 6:11:16: WebClient failed attempting to access https://aka.ms/vs/16/release/installer via 127.0.0.1
VisualStudio Bootstrapper:2021/1/14 6:11:16: Download failed using WebClient engine. System.Net.WebException: 无法连接到远程服务器 ---> System.Net.Sockets.SocketException: 由于目标计算机积极拒绝，无法连接。 127.0.0.1:443
在 System.Net.Sockets.Socket.DoConnect(EndPoint endPointSnapshot, SocketAddress socketAddress)
在 System.Net.ServicePoint.ConnectSocketInternal(Boolean connectFailure, Socket s4, Socket s6, Socket& socket, IPAddress& address, ConnectSocketState state, IAsyncResult asyncResult, Exception& exception)
--- 内部异常堆栈跟踪的结尾 ---
3、根据上面日志，得到原因是aka.ms这个域名打不开，因为这是微软的一个短域名。
4、将此域名对应的地址以及名称加入到本机Host：23.33.170.86 aka.ms
5、具体怎么加入到host自行度娘。
备注：
如果上述方案还不行，自行度娘修改本地IPV4的DNS，上面8.8.8.8，下面114.114.114.114，上和下可以反过来。