Google Fiber Link Regularly Reset when I block Private networks and loopback addresses??

Here's some information.

- I had Google Fiber installed yesterday.

- I have a powerful-enough pfSense setup.

- I also have ATT fiber at the moment (making the switch for pricing reasons).

In order to test the connection, we plugged a computer directly into the ONT and ran speed tests. This shows me that the ONT does not require the traffic to be tagged on a vlan (because the laptop I have surely wasn't tagging traffic). However, when I plugged the router (pfSense) into the ONT, I see the link being reset every 30-45seconds or so.

After some troubleshooting steps, I disabled the "Block private networks and loopback addresses" on the WAN interface (that was plugged into the ONT). At this point, the interface connects and maintains a connection.

What would cause this kind of behavior? I have used the same settings on ATT fiber (blocking private networks etc.) with no problem. Then I move the cable to the GF ONT and mayhem ensues.

I would be happy to provide more information as possible, I'm just not sure exactly what more to provide.

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Essentially: When I don't "block private networks and loopback addresses" the connection works. When I "block private networks and loopback addresses" the connection resets over and over again.