While being connected via WLAN, syslog contains repeated occurrences of this
message:
NetworkManager[1914]: <info>  connectivity: check for uri
'http://conncheck.opensuse.org' failed with 'Error resolving
'conncheck.opensuse.org': Name or service not known'

However when I do a nslookup on conncheck.opensuse.org, I get:
Non-authoritative answer:
conncheck.opensuse.org    canonical name = migration2.opensuse.org.
migration2.opensuse.org    canonical name = proxy.opensuse.org.
Name:    proxy.opensuse.org
Address: 195.135.221.145

And dig says:

; <<>> DiG 9.9.9-P1 <<>> conncheck.opensuse.org
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 23024
;; flags: qr rd ra; QUERY: 1, ANSWER: 3, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;conncheck.opensuse.org.        IN    A

;; ANSWER SECTION:
conncheck.opensuse.org.    281    IN    CNAME    migration2.opensuse.org.
migration2.opensuse.org. 281    IN    CNAME    proxy.opensuse.org.
proxy.opensuse.org.    123    IN    A    195.135.221.145

;; Query time: 775 msec
;; SERVER: 192.168.179.1#53(192.168.179.1)
;; WHEN: Sun Sep 03 00:56:17 CEST 2017
;; MSG SIZE  rcvd: 112

So what's wrong? (the WLAN is upp without an error all the time, BTW)