Nexus 6 on AT&T reportedly beginning to receive the Android 5.1 Lollipop update

That has apparently changed with the Nexus 6 though. All the Nexus 6 devices in the North American market have the same guts, the same radios, and it looks like Google may have a lot more control over pushing out system updates – though for now, we will reserve judgment.
Well, it looks like the Nexus line is on the up-and-up for updates across the board as some AT&T customers with the Nexus 6 have started to see the update offered to their device. Denoting build number LMY47D, the same build that is currently pushing to the Nexus 5.
Given what has obviously been a period of growth for pure-Google user base, these system updates are offered in phases to random devices. If you did not receive a notification of the update, check for updates in the settings. If that does not work, you just need to wait for the OTA, as there is a method to Google’s madness.
sources: Android Guys via Android Headlines