This issue occurs when Microsoft Skype for Business uses Citrix RealTime Optimization Pack 2.0.
When this issue occurs, Desktop Sharing, Application Sharing and File transfer sessions that require media relay servers for media traversal fails to establish. Additionally, you receive one of the following error messages on the conversation window:
We couldn’t connect to the presentation because of network issues. Please try again later.
Network Issue Error in Transfer
To fix this issue, install the June 7, 2016 update (KB3115033) for Microsoft Lync 2013 (Skype for Business).
Note Lync 2013 was upgraded to Skype for Business in April 2015. And Citrix RealTime Optimization Pack 2.0 requires the Skype for Business client.