The long-standing Nougat WiFi issue in Nexus 6P and Nexus 5X finally seems to have been fixed by Google. The Issue 221056, as reported by various Nexus 6P and Nexus 5X users, was causing devices to disconnect automatically from WiFi, and even break visibility of WiFi networks after a while after reboot.
The device would continue to to scan for WiFi networks, endlessly, causing battery drain. Third party apps were also not able to fix the issue, which thankfully didn’t affect Bluetooth and mobile connectivity.
The issue was marked by Android team as ‘Future Release‘ today, meaning they have the fix with them, and ready for sending as part of next update. So, the next Nexus 5X and 6P monthly update should fix the WiFi issues for you.
Also to be noted on the thread page is that some Nexus 6P users are reporting the issue as fixed already (not 5X users, not one, BTW). But anyway, as we said above, the next batch of updates should fix it completely.
This issue was first reported by a user in build NRD90M in late August 2016. The issue was not addressed in subsequent updates by Google, but users seem to have been pacified after the latest update, NPF26F — 6P users with this build reported the issue as gone. However, it’s early to give a judgement as more users are yet to upgrade at this moment.
If the latest update didn’t fix your problem, you may want to read about some suggested fixes for WiFi Nougat issue here.