That's pretty good from what I've seen from AT&T. Do you know if you are connecting to both DoD and C-band when getting those speeds or just one or the other?
Do you know how far away you are from the site and how much speed is lost when you get farther away? Based on my experience with T-Mobile and Verizon, at 3.45 GHz and 3.7 GHz I would expect over a gig when outdoors and very close to a tower, but I don't really know much about how AT&T is configuring their network. With T-Mobile, speed over distance has been improving with a n41 and n25 combo from what I've seen in my travels
Anything of note when on low band n5 at 850 MHz? T-Mobil's n71 is impressive, but and I will repeat this over and over, the tower density kills the service for me.