Netgear c7000v2 bridge mode

hi experts,

my old cable modem went out so i bought a new one (Netgear c7000v2) ... before this new one, my setup was cable modem > google wifi - everything worked great.

with this new one, since it's a cable modem/router combo, i now have 3 wifi (one from my existing google wifi, 2 from this new router 2.4 and 5ghz) ... most of my existing devices (phones,pc,tv...etc.) still connecting fine to my google wifi ... until a few days ago, and today ... some of them started disconnecting/lost connection...etc...my ps4 showing NAT as type 3.  i checked around for advices and some said i'm experiencing "double NAT" because i have 2 routers, and  the Netgear c7000v2 need to be set as "bridge mode" ... i can't find it in my netgear settings, called comcast and they said only netgear can turn that mode on (????)

could someone please let me know what i should do? I was thinking about bringing it back and exchange for a modem only version-but BestBuy won't let me to bring it back for another month (safety reason), they won't do that curb side ...  

thanks experts,