An unusual bug is currently breaking iPhones’ wifi connections. Luckily, it’s easy enough to avoid—and to fix if your phone becomes afflicted—but dang, is it weird. In short, for some reason, if your iPhone connects to a wifi network named “%p%s%s%s%s%n,” the device’s wifi will cease to function. So don’t do that.
Security researcher Carl Shou first identified the bug and posted the discovery on Twitter. Several other users followed up with their own tests confirming the issue. In each case, the network name alone broke their iPhone’s wifi features and prevented them from connecting to other networks. Worse, the testers found the bug persists even after rebooting an affected iPhone.
Strangely, this bug does not affect other network features, such as Bluetooth or mobile data. Connecting to the so-named wifi network on Android likewise has no effect; the bug seems to be rooted in either the iOS operating system or the iPhone’s hardware, but no one has yet to discern why this particular SSID breaks the iPhone’s wifi features.
Thankfully, the issue can be easily fixed if your iPhone has encountered it: Just go to Settings > General > Reset and select Reset Network Settings. This deletes all saved wifi connection information, so you’ll have to set up a new connection the next time you reconnect to a safe network, but it also immediately reverses the error.
While fixing the wifi bug is simple, preventing it is more involved.
Obviously, avoid connecting to networks or name your home wifi “%p%s%s%s%s%n” and warn others if you notice public wifi spots using that particular SSID. However, as our pals at Gizmodo point out, it’s possible other seemingly benign network IDs could trigger the same malfunction. That leaves iPhone owners open to trolls, malicious actors, or even unsuspecting users accidentally giving their public wifi connection a buggy name. So generally, avoid networks with lots of “%” symbols in the name, and notify a network’s admin if you encounter the bug after connecting to a public network.
If the bug is prevalent enough, it’s likely Apple will issue a patch to fix it. Of course, it’s also possible this issue can’t be fixed—and even if it can, it’s each user’s own responsibility to keep their devices safe in the meantime.