I started having the same issues at work a couple weeks ago, made the report and found it was already reported.

Turns out IT had changed where some of it's wifi APs were, and my office is now in the middle of two nearly-equally low powered APs. Every time a truck passes by outside it drops the signal and potentially changes which AP it's connected to, which caused a reboot on occasion. (It took me days to figure out it was trucks/signal causing this...) I "fixed" it by removing the work AP listing entirely and just not connecting to wifi at work.

I just loaded up todays build and re-enabled the work AP. Will let you know if it reboots again in the near future. Lots of trucks are due to pass by in the next couple hours.

Update: Lots of trucks and wifi up/downs later, and no reboots. Will let you know if that changes, but so far, so good.