[drivebycomment]

There are many possible reasons for a network traffic between two endpoints to not saturate your connection throughput to your ISP, and unless you can rule out all those other reasons, you can't just conclude that the lower throughput is due to any kind of deliberate throttling. I'm not saying they are NOT throttling. I'm just saying what you said is not enough evidence.

It's true Comcast has been caught doing a packet forgery - https://www.eff.org/wp/packet-forgery-isps-report-comcast-af... . If ATT is also doing it, it should be straightforward to collect evidence. So is there any evidence collected that shows ATT is doing packet forgery ?