Cannot connect to phone system: rebooting DC/Lync Server breaks AES/Lync

[dpentr]

Hello all,

We've been running into an issue when we patch our Lync servers or domain controller, where we reboot after patching and this reboot breaks the AES server in a fashion that causes Lync to function improperly with its phone integration.

Rebooting the AES server will restore functionality, but we usually don't know about this issue until a user reports being unable to use Lync's Click-To-Call function.

They receive the error "No Phone System Connection: Cannot connect to phone system".

Services on both Lync servers and AES all appear functional while it is behaving poorly, and there are no symptoms in the AES management interface log files.

Has anyone run into a similar issue with this? If so, can you please provide details of your own experience so I can help determine the cause of what is breaking the AES link specifically?

Thank you!
-David