Dear,
The error only appears when I have enables AdGuard. If I disable it, everything works ok. The problem is that I did not change anything before and after upgrading to 4.9.0 version. And it has stopped working on its own.
I have another Flint 3 in other home that still has the 4.8.4 version, configured like the other broken Flint 3, and everything is going ok. This is the reason why I still have not upgraded it to 4.9.0
If I go to DDNS page:
And click on DDNS Test, I always get this error:
And Log says:
Fri May 29 15:27:35 2026 user.notice AdGuardHome[12415]: 2026/05/29 13:27:35.249081 [error] dnsproxy: exchange failed upstream=1.1.1.1:53 question=";ifconfig.me.\tIN\t A" duration=497.293µs err="exchanging with 1.1.1.1:53 over udp: write udp 79.112.43.27:50121->1.1.1.1:53: write: invalid argument"
Fri May 29 15:27:36 2026 user.err ddns-scripts[27747]: glddns: cURL Error: '6'
Of course nslookup to google fails…
Also if I go to AdGuard Home and change the Upstream DNS, when I click on “Test upstreams” button also fails:
The same test, in the other router Flint 3 with 4.8.3 version, this tests works without any problem