Rancher Server HA mode

Do rancher support HA with Self signed certificate?

In documentation, it says as below and nothing has been mentioned about HA setup

USING SELF SIGNED CERTS (BETA)
DISCLAIMERS
This configuration will work for the ‘core’ services in Rancher running in a standalone mode (Non-HA setup). Currently, none of the certified Rancher templates from the Rancher catalog are supported.

So can I assume that its not supported?

Also I was able to bring an HA with 2 nodes with certificate bought from third party, which are working fine. But an old documentation says rancher need minimum 3 nodes for HA setup, but it seems to be outdated. Can someone please confirm?

Thanks