Although I have purchased Internet Connectivity menu, I can not connect SSH from the Internet to the virtual server.

There are no specifications that deny SSH connection in Internet gateways, logical networks, etc.

The most common reasons for failing SSH connection from the Internet are as follows.
・In the virtual server to be destination, the setting for SSH connection has not been established
・In the Managed Firewall, communication can not be permitted
・In the Internet gateway, routing settings are incorrect

For each setting method, please refer to the following link.
Tutorial - Managed Firewall / Managed UTM