The best you get is a "passthrough" mode where a router behind it will get assigned the public-facing IP so it doesn't ultimately behave like double-NAT, but the gateway still maintains an internal NAT table for everything going across.
You can't just use your own VDSL modem or plug your own router into the fiber ONT, as AT&T uses 802.1x auth and the key is burned into the gateway hardware.
The best you get is a "passthrough" mode where a router behind it will get assigned the public-facing IP so it doesn't ultimately behave like double-NAT, but the gateway still maintains an internal NAT table for everything going across.
You can't just use your own VDSL modem or plug your own router into the fiber ONT, as AT&T uses 802.1x auth and the key is burned into the gateway hardware.