Server1 shuts down unexpectedly. You need to ensure that when you start Server1, App1 continues to run on Server2. Solution: From the General settings, you increase the priority of Server2 in the Pref

Increasing the priority of a node in the Preferred Owners list only influences the starting or manual movement of a clustered role, not its automatic failover behavior when a current owner node unexpectedly fails.

The "Preferred Owners" list in a Windows Server Failover Cluster determines the preferred order of nodes for a clustered role when it is started or moved manually, but it does not dictate automatic failover behavior in response to an unexpected shutdown of the current owner. For App1 to automatically run on Server2 after Server1's shutdown, the clustered role for App1 needs to be configured for high availability, allowing it to fail over to any available node in the cluster, which is generally the default if failover is enabled.