1= As Jon pointed out you need a port forward.
2= your modem is most likely using port 80 so it is most likely block by modem.
( ISP wants money for that kind of thing.)
would not be surprised if port 443 is blocked too.
Would try none standard port for nginx. and port forward
You have a lot of possible problems. nginx config?
Good luck
I have Comcast commercial service. The cable modem has an “advanced” and “basic” bridge mode. Since I don’t what these are, I have shut down everything on the modem, including NAT and I have DMZ’ed everything to my server. All ports should be open to my ipFire server. The cable modems are cryptic on their settings with little information on what the consequences are. It did work OK on my previous server.
I have tried all kinds of port forwarding rules on ipFire, without success.
I have Comcast home and have the cable modem set to bridge mode. But there is no “advanced” and “basic” modes. NAT turns off in bridge mode which is good!
This wiki article should open the IPFire port 80 to a GREEN network device.
I’ve used this Wiki article to open a different port to GREEN and it worked as expected for me. I don’t know how a port forward to DMZ/ORANGE is different.