I have two instances (adfs1.xxx.com & adfs2.xxx.com) on a farm (sts.xxx.com) with WID (Windows Internal Database) setup, and am testing a failover situation.
Both are ADFS4.0 on Windows Server 2016.
When I stop the primary instance (adfs1.xxx.com), I expect the secondary instance to become the primary, and our client is able to continue accessing the login page (sts.xxx.com/adfs/ls/IdpInitiatedSignon.aspx).
However, it seems the failover does not happen automatically - the secondary instance still remains as a secondary and the login page (sts.xxx...) stops working.
Am I missing some configuration steps required to make it automatically failover when the primary instance is dead?
Authentication will still work. The only difference is that WID is RO so you can't update configs. on a secondary.
If you want "automatic failover", switch the DNS and make the secondary the primary manually.