C6300 trying to logon to wifi, says incorrect password

This would be your forum.

https://community.netgear.com/t5/Cable-Modems-Routers/bd-p/home-cable-modems-routers

Maybe the wif password is wrong?

You can hardwire into the the C6300 and login into the gui without needing the wifi password. From here you can change ssid and password. Or it could be that your other devices have the wrong wifi password save. Try both the resetting the wireless password as well as going into your devices, forgetting the wireless, and re-logging into it. 

https://kb.netgear.com/23439/How-do-I-change-my-NETGEAR-router-s-WiFi-password-or-network-name-SSID