当我去执行这段代码:yum install -y epel-release,报此错

sudo sed -i -e "s|mirrorlist=|#mirrorlist=|g" /etc/yum.repos.d/CentOS-*
[root@localhost 桌面]# sudo sed -i -e "s|#baseurl=http://mirror.centos.org|baseurl=http://vault.centos.org|g" /etc/yum.repos.d/CentOS-*
[root@localhost 桌面]# yum install -y epel-release
^[^ACentOS Linux 8 - AppStream                                                      [               ===                                                        ] ---  B/s |   0  B     --:-- CentOS Linux 8 - AppStream                                                                                                                                   0.0  B/s |   0  B     01:30    
Errors during downloading metadata for repository 'appstream':
  - Curl error (7): Couldn't connect to server for http://vault.centos.org/centos/8/AppStream/x86_64/os/repodata/repomd.xml [Failed to connect to vault.centos.org port 80: 拒绝连接]
错