The manual states
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Embedded Service Provider Metadata

If you change the base URL of the Identity Provider, all Access Manager
devices that have an Embedded Service Provider need to be updated so that
new metadata is imported. To force a re-import of the metadata, you need
to configure the device so it doesn’t have a trusted relationship with
the Identity Server, update the device, reconfigure the device for a
trusted relationship, then update the device. The following steps explain
how to force the Access Gateway to re-import the metadata of the Identity
Server.

In the Administration Console, click Devices > Access Gateways > Edit
> Reverse Proxies/Authentication.


Select None for the Identity Server Cluster option, click OK twice,
then update the Access Gateway.

Click Edit > Reverse Proxies/Authentication.

Select an Identity Server configuration for the Identity Server
Cluster option, click OK twice, then update the Access Gateway.
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I have installed an access manager APPLIANCE, there is not an option to
select "None" in the "Identity Server Cluster option".

How do we get the new metadata imported on an access manager 4.0
appliance?