The IP addresses resolution (DNS service) at Wikimedia does not work properly. The UNIX host commands gives no IP address.
...:~$ host www.nytimes.com
www.nytimes.com is an alias for www.gtm.nytimes.com.
www.gtm.nytimes.com has address 188.8.131.52
...:~$ host www.spiegel.de
www.spiegel.de has address 184.108.40.206
...:~$ host wikivoyage.org
wikivoyage.org has address 220.127.116.11
wikivoyage.org has IPv6 address 2620:0:861:ed1a::1
wikivoyage.org mail is handled by 10 polonium.wikimedia.org.
wikivoyage.org mail is handled by 50 lead.wikimedia.org.
...:~$ host de.wikipedia.org
Host de.wikipedia.org not found: 3(NXDOMAIN)
...:~$ host de.wikivoyage.org
Host de.wikivoyage.org not found: 3(NXDOMAIN)
Our host provider confirms that this is a problem of Wikimedia.