Thank you for your post I understand you're looking to get NAT type 1 port forwarding your PS4 on the Hitron CGN3_EN rocket modem. The PS4 behind any router is mostly going to only give you NAT type 2, check the following recommended summary below:
NAT Type 1 (Open) – You are either NOT behind a router/firewall OR you have already DMZ enabled. You shouldn’t run into any issues whilst gaming, but this may cause security issues.
NAT Type 2 (Moderate) your PS3/PS4 is connected properly and you shouldn't run into any issues.
NAT Type 3 (Strict) – You may be able to connect to the PSN and perform downloads/updates other functions may not work as intended.