I too am having issues getting the container to find the certs. I also have a google wifi. If i visit mydns.dnsserver.com:port during startup I get a message about the acme challenge so I know the port forwarding CNAME and DNS is working. All of my other services are working also externally by port number. I have a pihole in the mix as DNS only that i though was causing trouble but I removed it and got the same issues. I'm completely stumped.