we need more information on how your configuration for the Google Wifi ?
Looks like You have 2 different IP address for Wifi and Ethernet - when Google Wifi router connected to RV345, RV give different Address for Google Wifi, what IP address you get when you connect to google wifi from a client ?
Looks for me ( assuming that) you need a static route entry for the Wifi address space towards google ethernet Interface or IP address
also, provide what is the IP address working when you connect to ethernet?
what is the IP address you get when you connected to wifi (which is not working ?>)