Check the time on the device and your router. Some devices won't connect properly if the times are not in sync or at least close.
Also, here is an article that may offer some help. Unfortunately, it's basically reboot your router or revert to the password mode.
Have you looked as the wireless setup guide and followed the instructions? https://www.support.xerox.com/en-us/article/en/x_vlc400_en-O3328
You need to make sure that you configure the primary network or the device may not find the wireless network.