allow FQDN in IP blacklist\allow-list

[afit]

I suggest being able to add an FQDN as an allow within the IP Blacklist section. I'm currently having to manually change the IP in our many 3CX instances that we support. Being able to add an FQDN and then just change the DNS when required would be much easier and cut administration time. We currently apply this method on firewalls to secure remote access to our IP only.