Just want to share my experience with Helix and Google Wifi mesh network as when I was subscribing no one seemed to know if it would work or not. The short answer is it works perfectly - but requires some manual adjustments.
1. Set-up your helix wifi modem router using the app
2. Connect your Main Google wifi point to the Helix router ethernet with the red line marking
3. Restart the helix modem and then restart the Google wifi main point
4. Both HELIX and your Google wifi networks will now work at the same time which means you do not need to migrate all of your devices to a new network
5. Bridge Mode to ONLY have your google wifi network (and close the Helix wifi signal and simply use as a cable modem). I tried this and for some reason internet speeds on the google network were substantially slower than if I left it in normal mode. So after experimenting I now leave the HELIX with BRIDGE MODE DISABLED – so you will have a choice of either Helix or Google Network for Wifi.
6. YOU CAN connect your TV Helix devices to the Google Network. I have one TV connected to the Google wifi network and one to Helix wifi - and both work perfectly.