Hi community, my D717 seems to have SRTP / TLS communication problems. I'm using Zadarma PBX and trying to use the Snom phones but it does not work what ever I tried. SRTP is active with TLS I'm not really sure because the informations about it are irritating. 
Does anybody has experience with Zadarma and could get a new D717 to work? Same lines are working without any problem with the Zadarma app, Android and OSX VoIP apps. The issue is for sure not from Zadarma. 

Any help or advice is welcome

Thanks