If you move all the virtual machines and free the host, put it in maintenance mode, there are no problems.
Run one host at a time, always moving all virtual machines between the remaining host. in this way the NSX appliance is never turned off, so there are no interruptions.
However, these activities are always good to plan after working hours.
Put the host into maintenance mode to ensure no VM traffic is active on the host.
nsx_64_troubleshooting.pdf 3.7 MB
Disable DRS Affinitry Rule for NSX Controller VMs then you can migrate them to another ESXi host within cluster and then do place host in Maintenance Mode and do patching etc.