after parsing the domain name, it is found that if you want to access the domain name, you must add the port number to the specified domain name before you can access it normally. For example: www.xxx.com:3000,
ask:
how to enter the domain name directly to access it, and then you can access it without adding a port number such as www.xxx.com.

the server I am using is Aliyun"s ECS system is liunx centos7