Python pip安装失败"；找不到满足要求的版本“；

我正在尝试使用pip安装一些软件包，但错误如下

 pip3 install flask
Collecting flask
  Retrying (Retry(total=4, connect=None, read=None, redirect=None, status=None)) after connection broken by 'ProtocolError('Connection aborted.', ConnectionResetError(104, 'Connection reset by peer'))': /simple/flask/
  Retrying (Retry(total=3, connect=None, read=None, redirect=None, status=None)) after connection broken by 'ProtocolError('Connection aborted.', ConnectionResetError(104, 'Connection reset by peer'))': /simple/flask/
  Retrying (Retry(total=2, connect=None, read=None, redirect=None, status=None)) after connection broken by 'ProtocolError('Connection aborted.', ConnectionResetError(104, 'Connection reset by peer'))': /simple/flask/
  Retrying (Retry(total=1, connect=None, read=None, redirect=None, status=None)) after connection broken by 'ProtocolError('Connection aborted.', ConnectionResetError(104, 'Connection reset by peer'))': /simple/flask/
  Retrying (Retry(total=0, connect=None, read=None, redirect=None, status=None)) after connection broken by 'ProtocolError('Connection aborted.', ConnectionResetError(104, 'Connection reset by peer'))': /simple/flask/
  Could not find a version that satisfies the requirement flask (from versions: )
No matching distribution found for flask

我尝试安装了几个软件包（numpy、scipy和matplotlib），它们都失败了，并显示了类似的错误消息

我曾尝试在命令中使用include

--trusted host pypi.org--trusted host files.pythonhosted.org

，并使用easy_install，但都不起作用

这不是我的防火墙的问题，因为它关闭后仍然不工作

---

注：我使用的是虚拟环境，但这似乎不会影响结果。而且，当我试图通过浏览器访问时，大多数时候它会说无法访问该网站。

“当我试图通过浏览器访问pypi时，大多数时候它会说无法访问该网站。”这与pip无关。这才是真正的问题。把那件事处理好，然后这件事也应该解决。你知道我怎么处理吗？