If your IPFire box is behind the Google Fiber box, by default you have been double NATted.
This results in port forwarding failing to work properly.
The solution is to set your IPFire box up as a DMZ on the Google Fiber box itself:
- Log into your Fiber account (fiber.google.com)
- On the left, choose “Network”
- You should see your ipfire box connected to your Fiber box
- Select the ipfire box
- Expand “Advanced”
- Turn on “Reserved IP” (required for port forwarding)
- Turn on “DMZ”
Your IPFire box is now completely exposed to the Internet through the Fiber box.
Reference: https://support.google.com/fiber/answer/4650342