Cannot connect to devices

My modem is set up. I have a WiFi name and password. When trying to connect my devices such as phone or tv a message will say “unable to join.” On my phone a message will pop up and say “

This network is operating on Wi-Fi channels in use by several other nearby networks.

Restarting your wireless router may allow it to automatically choose the best channel to use, and may resolve this problem.“ I have restarted it twice and still not able to join.