第一步：1、用阿里云云安装wget
mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.backup
curl -o /etc/yum.repos.d/CentOS-Base.repo https://mirrors.aliyun.com/repo/Centos-7.repo
yum install wget

第二步：关闭防火墙
systemctl stop firewalld

第三步：查看dns：
cat /etc/resolv.conf
8.8.8.8
8.8.4.4
114.114.114.114

第四步：升级内核
yum -y install http://mirror.cloud.idcsmart.com/cloud/kernel/5.4.166/kernel-lt-5.4.166-1.el7.elrepo.x86_64.rpm

grub2-set-default ‘CentOS Linux (5.4.166-1.el7.elrepo.x86_64) 7 (Core)’

reboot
查看内核 uname -r