Lync Server IM MCU failed to connect to the SIP Front End. Local Machine name: %1 FE hostname: %2 IP address: %3 Message: ...

Lync Server IM MCU failed to connect to the SIP Front End.

Local Machine name: %1 FE hostname: %2 IP address: %3 Message: %4
Stack: %5

Cause: Lync Server IM MCU cannot communicate with the Microsoft Lync Server 2010 Front End Service over SIP due to network connectivity issues or unavailability of the Microsoft Lync Server 2010 Front End Service. This condition prevents setting up new conferencing sessions, forwarding Instant Messages and is disruptive and potentially fatal for existing conferencing sessions.
Resolution:
Please ensure network connectivity and availability of the Microsoft Lync Server 2010 Front End Service for the IM Conferencing Service to be able to function correctly.