The centos virtual machine cannot connect to the network, and restarts the network service to report an error. Please record the solution

The version of the Centos7 kernel installed by me is: 3.10.0-1062.el7.x86_64 and suddenly I can’t access the Internet. According to most of the tutorials on the Internet, it is generally divided into the following steps:

1. Close the virtual machine, click - "virtual network editor, as shown below

2,. After clicking to enter, you can see the following page:

     这里面有几个连接，我们经常使用的一般都是桥接或者NAT，关于这两者的详述，可以参考下这篇博文：

https://blog.csdn.net/ning521513/article/details/78441392/.

      在这里面需要强调一点的是：VMmet0、VMmet1、VMnet8对应的是网络连接里面对应的网口，当你选择桥接模式时最好是桥街道自己现在正在用的网卡上，如我这里使用的是无线网，那么你双击无线网再查看详细信息就可以看到对应的网卡：

3. Then go to the network card settings in the corresponding virtual machine to find the network card settings. If the bridge is selected above, then it will be as follows:

   然后还有另外一种NAT的方式就不在这里详述了，可以参考这篇博文

https://blog.csdn.net/CoderTnT/article/details/102642380

	但是我这里这次尝试了很多次还是无法连上，哦还要补充一点就是现在网上说的重启VM相关服务，也尝试过了，也不行，现象就是虚拟机网口一直都是down的， 并且重启网络服务还报错。如下图：

Finally, I refer to this blog post:
https://blog.csdn.net/crazy__qu/article/details/80535950

关闭了网络防火墙，成功解决，是如下两条指令：
systemctl stop NetworkManager
systemctl disable NetworkManager