Most media setup failures are caused by restrictions in place on the network or client computer. We look at these restrictions in 2 ways:
Deep packet inspection specifically SSL inspection - Skype ...
Updated Jul 13, 2017
Version 8.0
Blog Post
Sorry to say this. In the past, we have opened multiple tickets for the same issue. Still now there is no proper guidance to resolve this issue. Every one relayed on Ports, even we ports it is not working as expected. we have also checked the Skype call analystics after the meeting and it does show the error of the failure due to this reason. we are checking in CQD for the same time to identify the root cause. I don't know whether support can be proper guidance
error reported for this meeting during desktop sharing
Call failed to establish due to a media connectivity failure when one endpoint is internal and the other is remote