It doesn't matter what frequency devices connect at, they all join the same network and can talk to each other. If you can't see your Google home devices then there's another issue.

Actually it does matter.

When you set up the Google Home, it remember the frequency (2.4 or 5) and ALWAYS connects at that freq. If your phone/ipad, that you want to control the HOME devices, is connected at 5mhz, and your GOOGLE HOME was set up at 2.4mhz.. the app wont see the devices. This was confirmed to me by Google. There is no way to force your phone, or the HOME to connect to a specific freq.

And since there is no way to seperate the bands into 2 distinct SSIDs, OR unable to turn off a band.. you are stuck.

@Brianhagen This also affects Alexa users. 

The accesories that you connect to Alexa require a 2.4GHZ network and requires that the phone/tablet also be connected to the 2.4GHZ network.  Since all modern phones/tablets will prefer a 5GHZ network given the choice, you can not set the accessories up.