Looks like you are running double NAT, which is not recommended.
About DNS: I think Nest Wifi uses the ones specified at the top. The DNS server in the "WAN" section is probably what DNS server your router upstream/ ISP equipment (thus "double NAT") sends to devices when they request an IP address using DHCP.
"JOIN_AND_REGISTRATION_STAGE_SERVICE_ONLINE" I have no idea what means. This is an unofficial, undocumented API endpoint, so I fear we'll probably not get an answer from Google on this one.
I just wanted to jump in real fast to see if you saw olavrb's reply and to see if you still needed some help on this or if you were able to get it sorted out. If you are still needing some help, just let us know and we'll be happy to continue helping. Thanks for providing that helpful info, olavrb.
We'll olavrb's response is helpful. However, he also is not sure of the answer to my first question. He is also not sure of whether the one on top is really the DNS that my router is using. I think it would be better if you really have "specific" answers to each of the lines stated on the status report so that it could help us users determine which line to check to troubleshoot any issue of the router. Coz, for me, providing definition on each line on the status report could give us insights on what we can improve or change in our network to use the router more efficiently. If we can reach out to your developers to get the info I need, then by all means. Please do so.
Thanks for your the help, olavrb.
Felix_The_Cat, we appreciate your interest however; we don't have any news to share about that. We're always looking for ways to improve and we'll take it as feedback.
I also suggest that you send feedback by following this link. Let me know if you have other questions or concerns, otherwise I’ll be locking this thread after 24 hours.