What about using a standard range of ports? Isn't that something that can be done?
Alternatively what about allowing a user to select a port range for use on their server?
What about allowing a server to keep it's IP upon reboot instead of always changing it?
Saying you can't provide the range - that make sense if you are using a provider like Microsoft that always gives dynamic IPs. But if that's not the case, saying you won't provide your IP range is silly because you provide your IP every time you update the server's location - even though the DNS address doesn't update, I can see in my firewall the new address. So I could figure out your range eventually - it would just be a bit of work.