A user shares the user's desktop or an application with other participants through Skype for Business Online (formerly Lync Online). However, the participants in the conversation can't connect to the desktop sharing session. The user receives the following error message in Lync 2010 or Lync 2013:
A message that resembles the following entry is recorded in the Lync UCCP logs:
Cannot start Desktop/Application Sharing due to network issues.
ms-client-diagnostics: 23; reason="Call failed to establish due to a media connectivity failure when one endpoint is internal and the other is remote";CallerMediaDebug="application-sharing:ICEWarn=0x4000320,LocalSite=220.127.116.11:20702, LocalMR=18.104.22.168:54829,RemoteSite=22.214.171.124:62198, RemoteMR=126.96.36.199:51184, PortRange=1025:65000,LocalMRTCPPort=54829, RemoteMRTCPPort=51184,LocalLocation=1, RemoteLocation=2,FederationType=0"
To resolve this issue, follow these steps:
- Try to reproduce the issue by using one contact or multiple contacts. If the issue occurs for only one contact, determine whether anyone else can reproduce the issue with the same contact. If the issue occurs for multiple contacts, check for commonalities among the group of contacts.
- Important This step applies only to the Office 365 for enterprises and the Office 365 for professionals and small businesses plans. This step doesn't apply to Office 365 dedicated subscription plans. Don't use this step to troubleshoot this issue if you have an Office 365 dedicated plan.
Make sure that your network meets all the requirements for the best experience with Skype for Business Online. For more information, go to the following Microsoft Knowledge Base article:2409256 You can't connect to Skype for Business Online, or certain features don't work, because an on-premises firewall blocks the connection
- Verify that the video drivers are up to date and are working correctly.
This issue usually occurs because one or more of the following conditions are true:
- Port 443 or ports 50040-50059 are blocked.
- Traffic to or from meet.lync.com is blocked.