The FTP service established by Alibaba Cloud ECS Ubuntu16.04 is inaccessible to extranet

I've tried many methods but still can't access it from external networks. Please help! Initially, the FTP service was directly established for anonymous logon. When I tried to log on via the intranet, I was required to enter the username "anonymous" and a blank password. When I tried to log on via extranet, it failed. I thought it was a security issue, so I switched to user logon, and configured a new user. When I typed "ftp localhost" on the host, I could log on successfully. When I tried to log on via extranet and clicked "This computer" for connection, a logon interface popped up, but errors 200 and 227 occurred when I entered the username and password. If I used a browser, I could log on after entering the account and password, but I only had access and couldn't upload or download anything.

The following three pictures show my configuration (vsftpd.conf) information: