Some subdomain reports "NS_UNKOWN_HOST"

[M1scer]

From time to time i can not reach my subdomains and in the developer options i see the response: "NS_UNKOWN_HOST"
The most of the time this happens if i deploy a new service on a new subdomain, but today it also happens to an service existing for several month.

This is my ddns-updater config:

{
    "settings": [
      {
        "provider": "netcup",
        "domain": "domain.de, *.domain.de",
        "api_key": "abc",
        "password": "abc",
        "customer_number": "123",
        "ip_version": "ipv4",
        "ipv6_suffix": ""
      }
    ]
  }

I am running Traefik as reverse Proxy in front of all my services.

If i rebuild the ddns-updater container and start it again the issue will disappear.

Is this a known bug?
Is my config wrong?

Thanks.