I installed openxchange v7.8.0 on a Linux Debian 8. I have some valid licenses. But after installing open-xchange-meta-mobility, i can't connect to http://ox.mydomain.tld/Microsoft-Server-ActiveSync

I have this error :
"Proxy Error
The proxy server received an invalid response from an upstream server.
The proxy server could not handle the request GET /Microsoft-Server-ActiveSync.
Reason: DNS lookup failure for: localhost_sync"

Someone can help me ?

Thanks a lot and sorry for my ban english.