One of the NSX-T nodes reporting "Some appliance components are not functioning properly" and web page is down.
Also could be some errors on the screen like:
Component health: SEARCH:UP, POLICY:UP, MANAGER:UNKNOWN, UI:UP, NODE_MGMT:UP.
Error code: 101
First, CLI to the applience and check if next services status:
get service
If manager services for example is down tray to start it manually and if it fails check errors for manager.log using this command:
get log-file manager.log
get log-file manager.log
Assuming reboot alredy was in place.
If you need to detuch manangement plane:
For NSX-T 2.3 the command it:
detach management-plane
For NSX-T 3.0 it involes:
del nsx