A user shares the user's desktop or an application with other participants through Microsoft Lync Online. However, the participants in the conversation can't connect to the desktop sharing session. The user receives the following error message in Microsoft Lync 2010 or Microsoft Lync 2013:
Cannot start Desktop/Application Sharing due to network issues.
A message that resembles the following entry is recorded in the Lync UCCP logs:
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"
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.
Use the Lync Online Transport Reliability IP Probe (TRIPP) to make sure that your network meets all the requirements for the best experience with Lync Online. For more information about how to use the TRIPP tool, see the "How to verify that all network requirements for Lync Online are met" section of the following article in the Microsoft Knowledge Base:
Run the MOSDAL Support Toolkit, select Lync Online from the list of Office 365 services, and then click Next.
Enter your user ID and password, and then click Next. Your user ID and password aren't saved by MOSDAL and are only used to diagnose potential sign-in problems.
On the next screen, restart Lync, and then reproduce the issue by trying to start a desktop or application sharing session.
When the report is finished, locate the MOSDALREPORT.zip file in the Documents\MOSDAL library, and then contact Office 365 technical support.
Examine the Lync log files.
Open the MOSDALREPORT.zip file, and then under User_Applications, locate the Lync folder.
Use Snooper to open the file that's named Communicator-uccapi-0.uccapilog or Lync-uccapi-0.uccapilog.
On the Messages tab, look for the conference join attempt. This is indicated by INVITE sip:joe@contoso.com;gruu;opague=app:conf:chat:id:TF2497F37 SIP/2.0.
Directly under the join attempt is the server's response to your join attempt. It is indicated by ACK sip:joe@contoso.com:gruu;opaque=app:conf:chat:EF2497F37 SIP 2.0.
On the right side of Snooper, additional detail is provided from the SIP header. Sometimes, the MS-Client-Diagnostics field will contain additional information about the failure, as shown in the following example:
ms-client-diagnostics: 23; reason="
Call failedto establish due to a media connectivity failure
when one endpoint is internal and the other is remote"
;CallerMediaDebug="application-sharing:ICEWarn=0x4000320,LocalSite=207.46.5.9:20702,
LocalMR=207.46.5.63:54829,RemoteSite=11.1.111.11:62198, RemoteMR=65.55.127.64:51184,
PortRange=1025:65000,LocalMRTCPPort=54829, RemoteMRTCPPort=51184,LocalLocation=1,
RemoteLocation=2,FederationType=0"
This issue usually occurs because one or more of the following conditions are true:
Port 443 or ports 50000-59999 are blocked.
Traffic to or from meet.lync.com is blocked.
If the error message in the "Symptoms" section is present in the UCCP client logs for Lync, there's likely a communication error between two Lync edge servers. This means that two users who try to connect are connected through different edge servers that can't communicate with one another.
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