By default, Citrix XenDesktops will shutdown 3 hours after losing contact to a Citrix Desktop Delivery Controller, if there is no resumption of communication. For this reason, here are a few recommendations:
1) Monitor the ‘Citrix Desktop Delivery Controller Service’ service
There is always a chance that this can terminate unexpectedly (as we have seen happen be it due to antivirus, software bug/glitch …)
2) Set the ‘Citrix Desktop Delivery Controller Service’ service to keep trying to restart
By default the service may be set to do ‘Take No Action’ on failure, set it to ‘Restart the Service’ on First, Second, and Subsequent failures.
3) Have two or more Citrix Desktop Delivery Controllers (all on exactly the same versions of Citrix and at the same patch level)