Turn off the devices you want to connect to the network. Wait for about 10 seconds, and then turn on the devices in the following order; wireless router, computer or smart device, and then printer. Move the printer and computer or smart device closer to the wireless router to help with radio wave communication, and then try to make network settings again.
Select Settings > Network Settings > Connection Check, and then print the network connection report. If an error has occurred, check the network connection report and then follow the printed solutions.