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See also: https://learn.microsoft.com/en-us/azure/active-directory/devices/howto-vm-sign-in-azure-ad-windows
When you create a session host in your hostpool, make sure the name is unqiue in your tenant. If the same name is used in the same Azure tenant, azure ad joining may fail due to conflicting names.
In the virtual host pool, the RDP properties have to be costomized in case MS Entry ID is used to login:
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