I tried AT&T fiber for a month, but it's a never-ending arms race between their absolute piece of shit gateway and the new methods people develop to bypass it. In the end I went back to the awful 15mbps upload of cable I could use with my own equipment, over the symmetrical gigabit fiber with a mandatory gateway (with a rental fee) which I'd only use in "passthrough mode" that still runs every packet through a state table that maxes out at 8000 entries. I was paying rent for a device whose only purpose was to authenticate to their network and throttle my traffic.
Still bitter about it, clearly lol. I'd pay 4x as much if I could just get an ONT.
If you don't mind the state table and rental fee things, you'll probably be fine. Just be sure to run everything behind the gateway behind your own firewall, since AT&T can log into it and change whatever they want any time.