Double NAT/Unsuccessful UPnP xbox error

With all my searching it appears there hasnt been a solution but just in case I missed it I wanted to see if anyone had any feedback for this issue.  Im running the LB1120 to my google wifi and from there I have an ethernet cable to the xbox.  I get the double nat issue which still allows me to use it fairly well but would prefer to have it fixed to open.  If I put the modem in bridge it still reads a double nat.  If I plug the ethernet straight from the LB1120 to the xbox I get the unsuccessful UPnP error.  My IP from the ATT service is a 177.# and everything in general works just fine other than the NAT trouble.  Anyone have a solution or is it a lost cause?

Thanks