Ddns with usb-tethered android smartphone

I'm using an android smartphone for usb-tethering on a raspberry pi with actual openwrt.
So far so good.
But I'm not successful with ddns-service.
Why does the client try to update the local interface-ip to my provider.
Can anyone give me a hint?

Here's the log from /var/log/ddns:

171208       : last update: never
 171208       : Detect registered/public IP
 171208       : #> /usr/bin/nslookup heckenweg.spdns.eu  >/var/run/ddns/HeckenwegSPDYN4.dat 2>/var/run/ddns/HeckenwegSPDYN4.err
 171208       : Registered IP '' detected
 171209  info : Starting main loop at 2021-11-29 17:12
 171209       : Detect local IP on 'interface'
 171209       : #> ip -o addr show dev usb0 scope global >/var/run/ddns/HeckenwegSPDYN4.dat 2>/var/run/ddns/HeckenwegSPDYN4.err
 171209       : Local IP '' detected on interface 'usb0'
 171209       : Update needed - L: '' <> R: ''
 171209 ERROR : No or private or invalid IP '' given! Please check your configuration
 171209 ERROR : No update send to DDNS Provider
 171209       : Waiting 600 seconds (Check Interval)

Because youre CGNATed by the carrier?
As long as you are, it won't work.

But the ddns-client trys to update/send the local interface address of the android smartphone at usb0....
Sorry, but is this CGNAT?

On the tethered smartphone I see/got a public ipv4-adress...

The smartphone runs a network for tethered users and NATs them to the Internet. I don't think there is any way to change this in the phone.


I think i can use an android-app on the smartphone to update the ip, but this is not the way I wanted to use this "project"... :frowning: