Just had an ONT type 300 modem/router installed for fiber, and my NAT has gone from open to moderate (previously on a double NAT router+mesh network which was setup for DMZ+port forwarding) 

Called the ISP who said the only way to get an open NAT was to pay more per month for a static IP.  

ONT block access to the new modem/router so you can't change the settings yourself, but my understanding is that if I had access to this I could setup a DMZ/port forwarding on it to have an open NAT without their input at all.

Anyone else have an issue with NAT and fiber? This seems totally unfair that instead of changing the settings on the router (either doing it themselves or letting me do it. A whopping 5 minutes of any ones time), they want to charge additional money for something that isn't required.