Hey @Fred_von_Lohmann1,
Thanks for giving that a try! I would next check your Nucleus Web UI to make sure that you have valid DNS servers setup there and then if the issue is still ongoing after checking the WebUI DNS, I suggest you change your router’s DNS servers from the ISP provided ones to Cloudflare DNS , Quad9 or Google DNS.
Can you please give this a try and let me know if it helps? With that, do you have any third-party firewalls/ VPNs or additional network gear at play?
Thanks!