A hosting company contacted the German Volunteer Email Response Team (ticket #2015081910012338) as they are having problems reaching Wikipedia from some of their networks. It seems that ge-2-5.br1-knams.wikimedia.org refuses the connections e. g. from their subnet 18.104.22.168/18.
Are requests from that network blocked by the WMF infrastructure?
traceroute output and contact information of the hoster are available in the linked OTRS ticket. If you don’t have access to that ticket, please contact me via Wikimail. (I don’t want to post this information in a public issue.)