I have just bought two of the Nest Cam (battery). I already have a nest doorbell which works fine.
I have tried for two days one many occasions to get the first of the Cams to set up. I get right through to it trying to connect to the door bell but it always fails. the nest doorbell and my phone are both on the same Wi-Fi network and talk to each other.
having read other posts, I brought the Cam closer to the doorbell but this made no difference.
the message I get is posted below.
Can't connect to assisting
We're having trouble connecting to Front Door.
Make sure that it's online and connected to the
same Wi-Fi network as your phone, or remove
this device if it is no longer in your home.
We've been lucky not to have encountered the "can't connect to assisting device" problem that's affected so many Google Nest customers. There have been many posts on it in this forum.
Here is a shorter recent thread that discusses some of the workarounds that have worked for some customers:
I am terribly sorry to hear that you're having this issue with your Nest camera! I'm sure it's frustrating but I'm happy to look into this and see how we can help out. The first troubleshooting step that I'd recommend would be to Restart your device. By doing this, it should keep all your settings, and reconnect it to the same Wi-Fi network. This is helpful if it ever freezes, has connection problems, or isn't working normally.
Solution found. Problem caused by Interference from a cordless analog telephone base station.
I experienced the "Couldn't find an assisting Nest device" error today while trying to set up a new Nest Outdoor/Indoor Camera Battery.
The Nest support assistant asked me if my camera was near an analog wireless device such as a baby monitor or a cordless landline telephone. Yes, the camera was near my cordless telephone base station. He asked me to move the Nest camera a few meters farther from the cordless base station to avoid possible interference. I moved the camera, retried the Google Home device setup, and the setup worked flawlessly.