If you have frequent problems with your users getting blocked by the firewall the safest way to prevent that would be by adding your country to the ignore list.
In the file /etc/csf/csf.conf under CC_IGNORE = "" add your country, example for Croatia
CC_IGNORE = "HR"
You can check for your country code here (two-character code)
https://www.iban.com/country-codes
https://countrycode.org/
after adding your Country you would need to restart the firewall
csf -r service lfd restart
This will not whitelist or open ports for your country but in the safest way, it will prevent any client from your country to get IP blocked.
We don't recommend having this option enabled for hack-intensive countries like Russia, China, US, and similar.