I've see a few posts here about trying to connect to google home but nothing regarding your specific problem.
I can't even find anything on your specific error message with a google search, which is very unusual, so I can't get any clues to what the underling problem might be.
Hi @Shaun1985, is it only the Google home devices not connecting to the Wi-Fi? How about other devices like your mobile, computer or tablet? How many total devices are already connected and how many are you trying to connect? Have you checked the modem Wi-Fi settings using the IP address? So there will be a sticker either at the bottom or the back of the modem with IP address and modem login username / password. Enter the IP address in any one of the browser to login.
You can also try modem reset by pressing the reset button at the back of the modem for 10 secs.