AT&T Fiber in the SF Bay Area is flipping bits

Re:AT&T Fiber in the SF Bay Area is flipping bits by _rs on Wednesday December 09, 2020 @12:05AM (#25355561)

Ah ok - sounds like a double NAT then, not a bridge.

Edit: to go into more detail, their router is acting as a NAT for your public IP, giving you your first subnet, and then your router is getting a single IP on that subnet and creating a NAT where your devices all get IPs. In a bridge there would only be 1 IP space behind a single NAT. In your case with a double NAT a lot of consumer things might not work (like UPnP) and port forwarding would require you to add rules to both routers.

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Re:AT&T Fiber in the SF Bay Area is flipping bits by warent on Wednesday December 09, 2020 @04:10AM (#25356734)

Thanks, yes that's exactly what it is then. In order to give external access to my devices (e.g. my NAS) I have to forward ports from their router to my router, and from my router to the device. So, definitely double NAT. Amusingly the person who installed it incorrectly called it a bridge.

Thank you for the insight and lesson!

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