問題產生：無論是vs2019還是2017，都有可能存在進度條0%不動。
問題說明以及解決方案：
1、此問題和是否使用科/學上網並沒有關系，不用罵綠/壩。
2、在你的電腦里：用戶/AppData/Temp下找到你進度條不動的時候的日志打開它，你會找到一個堆棧報錯日志如下：
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 '無法連接到遠程服務器' - '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: 無法連接到遠程服務器 ---> System.Net.Sockets.SocketException: 由於目標計算機積極拒絕，無法連接。 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)
--- 內部異常堆棧跟蹤的結尾 ---
3、根據上面日志，得到原因是aka.ms這個域名打不開，因為這是微軟的一個短域名。
4、將此域名對應的地址以及名稱加入到本機Host：23.33.170.86 aka.ms
5、具體怎么加入到host自行度娘。
備注：
如果上述方案還不行，自行度娘修改本地IPV4的DNS，上面8.8.8.8，下面114.114.114.114，上和下可以反過來。