DDNS Script IP Update failed

Dear Community,

I use "normal" Dynamic DNS with duckdns.org to connect to a nextcloud server isolated in a DMZ .

OpenWrt 21.02.1 runs on a Linksys WRT1900ACS

log shows following error:

user.warn ddns-scripts[3818]: myddns_ipv4: Updating IP at DDNS provider failed - starting retry 345/0

I have to point out that everything works fine. However, i recon there should be no error message at all.
I guess the error comes up as updating is not possible/necessary as WAN-IP hasn’t changed.
Do you have suggestions to find the reason for this error and to stop this messages?

Thanks Stephan