This started happening to me for the first time ever, on my HP laptop I've owned for 2 years, a couple days ago. At first I thought someone had hacked into my WiFi, but looks like it's a known glitch.
http://www.drivethelife.com/windows-10/windows-10-airplane-mode-errors-and-solutions.htmlAirplane mode on or off issues arise and annoy Windows users after the Windows 10 upgrade or Windows 10 anniversary update. “Windows 10 airplane mode keeps turning on”, “airplane mode turns on by itself”, “Windows 10 airplane mode stuck on”, etc. are the main problems that Windows users complained in some forums.