same problem on oracle cloud, all ports open install without error, ping - ok, ubuntu 18.04
UPD: PROBLEM RESOLVED
First, you need to install firewalld
sudo apt install firewalld
Then open
sudo firewall-cmd --zone=public --permanent --add-port=8888/tcp
sudo firewall-cmd --zone=public --permanent --add-port=80/tcp
sudo firewall-cmd --zone=public --permanent --add-port=443/tcp
sudo firewall-cmd --zone=public --permanent --add-port=20/tcp
sudo firewall-cmd --zone=public --permanent --add-port=21/tcp
and other port what u want
Finally, reload firewall cmd
sudo firewall-cmd --reload
AND it works!