I am having trouble understanding upgrade options for Firepower 2100. I am runnign FTD software 6.3 on it. To my understanding it cannot be upgraded from FCM, which is an option for Firepower 4100 and 9300 series. I am trying to use FDM to upgrade it but the https access is not working and it is giving me Server Unavailable message.
Is FDM the only method to upgrade 2100? What is the way to enable local management capability on 2100 so I could use FDM. There is no link I could find that gives step-by-step upgrade procedure.