Can't add Nest WiFi router to existing Google Wifi network

[upstill]

I have an existing Google Wifi mesh network. I'm trying to add a Nest Wifi router to the network via Ethernet cable. Google Home recognizes the device, and I get as far as "Adding device to your mesh network" when it comes back and says "Couldn't add device...It could be that you have  2 devices wired to the same modem. Make sure all your devices are configured correctly..."

I am totally stuck. I most certainly have only one device (the root Google Wifi router) connected to my modem. I've factory reset every device on my mesh network and rebuilt it from scratch, and I'm still getting the same result. Help!

Many thanks for ANY suggestion for getting this to work.

[Yoyojammer]

I am getting the exact same issue today, I got a another access point to add to my existing network. Had to reset everything just to get my next work in the Google home app. Now I have the router up and main point working but the other two won’t connect at all, during the setup after a reset I get the same messages as you every time, not connecting via Ethernet just the standard Wi-Fi .. nightmare, I went to add one and now I am one down! I am thinking my older ones maybe are not talking because of outdated firmware, or could be todo with 2.4Ghz connection… no idea stuck now.. anyone out there able to help us

[upstill]

Yoyojammer, I just want to make sure you see my answer in reply to my post. I finally figured it out. If you need further help, feel free to contact me (my name here is the same as my gmail login).

[Jeff]

Hey upstill,

Thanks for sharing what worked for you here. That's really helpful for anyone looking looking for the same answer.

Hi, yoyojammer. I just wanted to check with you to see if you saw upstill's update and to see if that worked for you as well. If you're still having troubles, just let me know and I'll be happy to help.

Thanks,
Jeff

[Jeff]

Hey again yoyojammer,

I just wanted to follow up once more to see if you were still needing some help here. If so, just let us know.

Thanks,
Jeff

[upstill]

I finally got it to work and I learned two things (I think) which turned out to be crucial, AND which appear nowhere in any of the pages I hit on the Help site.

1) The error reported at the end of setup was related to the fact that I was connecting my new station to the existing station via Ethernet cable, and somehow Google Home interprets this as trying to connect to the modem twice. When I left them physically unconnected it worked as expected, BUT ONLY BECAUSE...

2) ...I halted and restarted the Google Home app after getting the error. 

You can indeed wire the stations together, but only AFTER getting them enmeshed (sic) wirelessly. I know this because one of my stations belongs WAY too far to connect wirelessly. After I brought it inside and added it to the network close to the base station, I took it out to the other end of a LOOOONNGG cable, plugged it in and it works a treat.

[Yoyojammer]

Hi all, sorry took ages to reply! Thank you @upstill for the information, yes I got it to work in the end.... in my case it was slightly different, I had the first one connected ok but because of the reset to the other two it all came down to the DNS settings, so on the first one in the google home app, under wifi settings, adv networking, dns settings, set to custom... add 8.8.8.8 as primary dns and 8.8.4.4 as secondary, after a restart the other two could then see the network and I was no longer getting the 'Couldn't add device' message, hope this helps someone else out as well one day! Thanks all 

[upstill]

Congratulations! So happy to be on the other side of this nightmare. God I hate networking.

[AbigailF]

Hello folks, 

Awesome — glad to hear that your issue is fixed. It looks like we can consider this one complete, so I will lock the thread shortly unless I can help out with anything else. 
Appreciate your help here, @Jeff.

Best, 
Abi