Port Forwarding Security "Intrusion Detection"

Just created a dedicated server for Satisfactory on my truenas system for my friends and I. In doing this, I had to forward a specific port so people (aka my friends) could join outside of my network. However, I have already received a few "intrusion detection" alerts since creating this rule. Is there a way to make the rule more secure where I allow only my friends to join securely?

Thanks!