Users who upgraded their UAG server to Update 1 may receive an error upon activation “Error: Trunk <Trunk name> cannot be activated due to the following: Invalid External Port address. Please choose a different port.”
This situation may happen if you are running a UAG array, and the array has a redirect trunk (from HTTP to HTTPS) configured. With Update 1, UAG now allows the user to select any external port on a trunk, but this functionality has not been fully enabled for a redirect trunk in Array mode and this may lead to this error being shown.
If you run into this situation, please open a support case with Microsoft CSS, and a support engineer will help you deal with the situation.