I want to block all communications that I do not allow when setting firewall function on the server. Please tell me the recommended setting of whitelist.

If you are going to use the Common Function GW, give permission to the communications to the network used in the Logical Network for the connection to the Common Function GW. You need to enable the periodical communications for the use of an NTP server and for the activation of the OS license as the network is for the service management.
On the other hand, as the Monitoring service monitors from the side of the service management platform, you do not need to consider the settings.

Reference: Service Descriptions - Common Function Gateway - NAT / NAPT function