I have an Alibaba ECS Ubuntu setup and everything works fine except that I cannot access my FTP from any other FTP client. I get the timeout error I have setup the ufw rules to allow incoming as well as tried disabling the firewall still the same error.
I can however login to FTP using localhost or private IP when am logged into the management terminal.
I have tried both vsftpd and proftpd.
Turns out that the firewalls settings done using sudo ufw through the terminal does not reflect at all. I had to use the ECS instance manage->security groups->add security rules (or use qucikly create rules to add multiple rules) to add desired ports and allow ips (0.0.0.0/0 ) to allow from any.
Conclusion: Use the ECS manage console to set firewall rules