[opensuse-support] DNS problems after upgrade 15.0 -> 15.1

Dear list, after upgrading from 15.0 to 15.1, DNS resolution does not work for most programs. It seems that NetworkManager is working correctly. The content of the /etc/resolv.conf is correctly updated with the nameservers in my LAN. The tools dig and nslookup also produce correct results. However, Firefox, Thunderbird, Nextcloud, ping, etc cannot resolve hostnames. Has anyone else experienced this? Is there a solution? Can it be related to systemd and its DNS resolution service? Thanks Sven *One other question: is there no Bugzilla anymore for Leap 42 and 15?