Want to create a bridge network with existing router
I think I'm reading all of the documentation before hand. And I do see on the app I should select Settings->Advanced->DCHP&NAT->switch from automatic to bridge.
But, stupid question is: Do I first have to go through the steps to shut off the modem and connect through the modem? I am terrified right now of overriding my router.
Just want to make sure I'm understanding your question. You want to setup the eero network and bridge the eero network correct? If you are trying to bridge the eero network you will need to setup the eero network first and then go into the settings you stated. Once the eero network is in bridge mode you will still have a separate network for all devices you would like to connect to but the management of those devices will be handled by the upstream router. If you are trying to use the eero network as a separate network and do not want to use your ISP router anymore then you would want to bridge the ISP router and not the eero.
Let me know if you have any questions. I understand this can be a scary setting and it should not be messed with casually.