Speedtest.net provides many different servers, most of which are not on the AT&T network. The IP is not in the AT&T space and the AS path leaves AT&Ts network.

Speedtest.net provides many different servers, most of which are not on the AT&T network. The IP is not in the AT&T space and the AS path leaves AT&Ts network. In the end until someone can provide a dump of what is in the routers settings it is all a guessing game.