My tablet (Nexus 9) downloaded and installed the android nougat over the air about a month back. But not my phone (Nexus 6p). It just upgraded to another version of Android 6 yesterday. Is it expected or something wrong?
I did some research and basically you need to give it a few days, if that doesn't help try flashing it. Here's a guide https://www.gottabemobile.com/2016/09/09/how-to-install-android-7-0-nougat-right-now/