The 4.50 firmware update for the PlayStation 4 has led to WiFi issues for some users. A lot of console owners report they’ve been unable to connect to a wireless network ever since installing the update.
Some say they’re receiving multiple “failed” notifications whenever they try to connect. In other cases, the console is claiming their WiFi password isn’t correct and is displaying the error code NW-31297-2.
It appears you can get around this problem by using a wired connection or by making your WiFi network unsecure, although that’s not a great solution.