PS4 error nw-31291-6 is an error that usually occurs when the user is unable to connect to a Wi-Fi network due to a weak signal strength.
Some of the solutions to this error include changing the router settings and using an ethernet cable or wired connection.
Please see our in-depth walk-through solutions below.
To access your router look for an instruction in the web using your router brand and model as a keyword. If the device is provided by the internet service provider (ISP) call your them for assistance.
Option 1. Change Wireless Mode
Option 2. Change Wireless Channel
If the error still persists, your modem router may require a restart to update the change. Unplug your modem router and your PS4 for at least three minutes.