Assume that you use Microsoft Lync for Mac 2011, and you accept a desktop sharing or video sharing session. In this situation, the session disconnects unexpectedly within 20 minutes.
Note The issue typically occurs when the data transfer rate for the session is above 800 kilobits per second (Kbps). However, the problem may also occur when data transfer rates are slower.
This issue occurs because TCP window size drops to 0. Therefore, Lync for Mac 2011 disconnects the session.
Note TCP window size reflects how much data a receiving TCP stack or a receiving application can process.
To resolve this issue, install one of the updates that are described in the following Microsoft Knowledge Base (KB) articles:
2844274 Description of the Microsoft Lync for Mac 2011 14.0.5 update
2836517 Description of the Microsoft Lync for Mac 2011 14.0.4 Hotfix 1
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