I've still been having a couple of issues with my Nexus 5X (unrooted).  The version of Nougat I initially downloaded through the Beta program was NRD90R.
1) My phone 
sometimes gets really sluggish & takes so long to wake up when I put in a fingerprint or the pattern lock, that sometimes it doesn't fully wake up, & it dozes off again.  Could this be related to Doze?  I don't even know what to look at, it's very intermittent; sometimes happens on wifi, sometimes on mobile data.
2) Yesterday on my drive home from work I heard a beep from my phone so I took a peek, a system update had just downloaded.  
Over mobile data....  which drove my Google Fi usage up to 1.63 GB, & I'm on the 1GB/month plan (I was previously on track at just over mid-month & only using half my allotted data).  The new version of Android that downloaded is NRD90S.  How can I force updates to only install over wifi?  I'm on wifi all day at work, & all night at home, & the one time the download showed up was when I wasn't on wifi.  
Has anyone had either of these issues?  Any suggestions on where I can look to make settings changes to try to resolve either issue?
I did a factory reset after the initial Nougat update, I've been considering a 2nd one before I got yesterday's update, but I hat to do another if it doesn't actually resolve anything.