Thank you. There is no reason to redact the private ip since this is your private network, nobody can access 192.168.6.1 Anyway, I wanted to check that DNS and DOMAIN are set up.
But I cannot figure out the second screen (I don’t speak German). Usually, you define static ip’s from Network > Edit Hosts. I assume the static ip’s are all in the .6 subnet (but all of them are redacted) and also those static ip’s should be outside the DHCP range .150 - .200.
I guess I found the reason for the problem,
after I setup the setting of the NTP server and the WINS-Server, which is in my case the same as for the DNS server, the problem is gone.