You have a carrier grade nat IP. This are not full working IPv4 addresses because your ISP use also a nat. You cannot simple open ports from outside in your router because the router before the IPFire blocks it.
How can one tell they have a carrier grade nat ip?
Read up on it. Found it. Did not know it was a thing.
Because of the IP.
Correct. Checked. I’m behind IPS’s central router, by Carrier Grade NAT (CGN). I requested public IP.