This feature is not supported on firewalls. You can configure this feature only on an SMA appliance.
Prerequisites
To add an AOV connection profile
Create a connection to the user and connect. For more information about adding a connection profile, refer to the Adding Connection Profile Management section.
After connecting, the user can find the connection name will change to AlwaysOnConnection.
The server does not allow to disconnect.

The server allows disconnect.
The user can disconnect.
If users disable AOV in the server, the connection changes to normal after disconnecting.