The Anniversary Update for Windows 10 brought a lot of great refinements and features to the table. However, as far too many users discovered, it also brought with it a number of bugs. From the get-go, it began locking-up on users, ultimately pushing Microsoft to endorse user-submitted fixes. Later, the update managed to kill webcams, and somehow even made some Linux users' lives miserable. Fast-forward to now, four full months after the Anniversary Edition launched, and Microsoft is dealing with yet another bug - but this one should be fixable fairly easily.
Recently, some users have noticed (probably abruptly) that their Wi-Fi dropped out, with Windows complaining about an invalid IP configuration. Microsoft released a patch just the other day (who enjoyed a good ol' fashioned forced reboot from it?) that could have fixed the issue, but didn't.
Current fixes are simple, as long as they happen to work for you. If you are on Windows 10 and without Wi-Fi, and a regular reboot doesn't help, hold down the Shift key as you click on the Start button and then choose to Shut Down (never letting go of Shift until the process begins). That will force the computer to shut down to a state where it will need to process a full boot cycle before you get back to Windows.
If that somehow doesn't work, or you want to try the alternative from the get-go, right-click the networking icon in your system tray and click on 'Troubleshoot problems'. The tool that spawns might help correct the settings.
These are far from ideal solutions and simply workarounds, however, so we hope Microsoft squashes this bug soon and issues the patch before the next Patch Tuesday, given the kind of hassle it's creating for people.