I had a problem yesterday caused by the reboot of an AES server after the installation of a service pack. After the server was rebooted we lost the Avaya T-Server link to it.
The problem was caused by a static IP route which was added a couple of months ago as a quick fix and this did not survive the reboot. This was then forgotten about.
The moral of the story is always fix the root cause of the problem there and then otherwise it will come back and bite you at some time in the future.