Whatsmyip.com and wan ip are different for nest WiFi pro

[cjoshi]

I am trying to setup DDNS for my synology NAS. 

The issue is I am not sure which public op to use. The WAN IP is definitely not private but whatsmyip shows different public ip than WAN IP from router’s setting. 

when I access use WAN IP for DDNS, I can access NAS from inside the network but not from outside. Although the public ip reported by whatsmyip does not work at all. 

[olavrb]

You might have what's known as double NAT; two inner networks, where the WAN IP obtained by Nest Wifi isn't your public IP, but a local IP, RFC 1918, received from your modem/router combo.

• https://dongknows.com/double-nat-vs-single-nat/

That said: It's not best practice to expose a NAS directly on the internet, consider other options like VPN or Synology QuickConnect (if you got a Synology NAS).

About Synology QuickConnect:

• https://mariushosting.com/category/synology-quickconnect/
• https://youtu.be/s9YguJ1SsTM

About hosting a VPN server on a Synology NAS:

• https://youtu.be/vBXlZf7gSwc

[cjoshi · Accepted solution]

Hi, thanks for the reply. I did look for the double NAT earlier but that was not the case and I was at least familiar with the concept.

After a little bit of research, It turned out that, it was a CGNAT turned on by the the ISP. I was not aware of the concept of the CGNAT. However once I reached out to the provider to remove the CGNAT, all started working fine. 

Also while exploring all this, I learned about your other suggestion of not exposing the NAS to the Internet. Yesterday I configured OpenVPN with some tight firewall rules and it's working like a charm. 

Thanks, again! 

[olavrb]

Ah, CGNAT, forgot about that being an option.

Good to hear you're all set. 👍