@mauro-tridici create an alias with your country or countries you want to allow, and or any other IPs
allow.jpg
This is the alias that is allowed to talk to my plex server. See I allow US Ips, also Morocco because I have a family member currently living there. Then some other IPs that are used to check if my plex server is up and if not warn me.
The reason for the other lists is because some of those IPs are not always from the US.. Many monitoring services use IPs from all over the planet to make sure your service is up.
That one labeled PlexRemoteCheck is list plex puts out for their IPs that validate your server is available remote - and it can be IPs outside the US as well.