Verizon Gateway Router in DMZ mode to allow STB to have TV guide, DVR etc..

[JamesRD1]

We got a new ONT from Verizon that allows us to have the cable TV run through coax and the internet run through cat6 (ethernet). My hope was to start benefitting from having the 2 separated as speeds get too fast for coax. So my current system runs both a cat6 line from the Verizon ONT in the garage and a coax line. Supposedly this allows a separation between the two. I checked this on line and is legit. Now, in order to use the google mesh wifi which we bought, I had to turn off the Verizon router wifi but still use it as the router. So the google wifi router is down stream from the Verizon router. The problem was this means we can't get TV programming guides or record shows on our cable TV which is no good. After an hour last night on the phone, the guy said we could set up a DMZ on the Verizon router which would allow the cable boxes to communicate again with the router through the coax I assume. 

So, I get a DMZ is a safety risk. My question is if the Verizon router has the DMZ on it, does my google wifi mesh firewall protect all my wifi. It seems to me like it would. That would mean the only vulnerable thing in my house would be anything hardwired into the ethernet. So it seems entirely backassward in that the wifi is safer than the ethernet but it allows the cable boxes to communicate. 

My sense is the easiest thing to do is to go back to basics and scrap the whole google wifi mesh. The google mesh also messes up the Sonos system so I am still working on something to get that to work again. (Wireless Sonos has its on mesh system that doesn't like other mesh systems). Now I could probably fix this by hooking up all the Sonos equipment to the ethernet. Again, no safety issues as I see it as l long as the google wifi router protects me from the DMZ in the Verizon router.

So in short, does having the Verizon Gateway router in DMZ mode put my wifi internet service at greater risk or does the Google wifi mesh router essentially create a new firewall so the wifi is as safe as it was when the Verizon Gateway router was the firewall.

My apologies in advance since I know nothing about tech and am sure I have a lot of terms and concepts wrong. 

Thanks,

James