Is there a power off order or method for NSX manager and NSX controllers that you need to use? Do you need to shut down NSX manager first or controllers first?
NSX Manager can be powered off and on without impact to the environment (aside from management of the environment).
This document details the power off/power on sequence for NSX:
VMware KB: Shutdown/Startup order of the NSX for vSphere 6.x environment after a maintenance window ...
