One small, typical example: most of our VPN customers are setting up some satellite that needs to connect to the home office. The connection is initiated from our network to the home office. So the IP address of the satellite doesn't really matter.
This is not always the case, but it is the most common case.
So when a customer demands a dedicated static IP address, I wonder if they really need that. We charge extra for that because we have a limited pool of public IPv4 addresses. We can do it, but it is usually unnecessary, and better to avoid unless you really need it.
The connection is initiated from our network to the home office. So the IP address of the satellite doesn't really matter.
I'd assume they're restricting access further by only allowing certain ips thru a firewall in front of the VPN server, or requiring extra auth factors from unknown ips, or something.
It's not needed but troubleshooting is much easier for the sysadmin from the mothership and 3$/month for a static IP is literally nothing for a business.
We also always get a static IP for everything, because what do you do If the vpn doesnt come up after a firewall reboot ans the IP changed?
This is not always the case, but it is the most common case.
So when a customer demands a dedicated static IP address, I wonder if they really need that. We charge extra for that because we have a limited pool of public IPv4 addresses. We can do it, but it is usually unnecessary, and better to avoid unless you really need it.