Merge pull request #103328 from mikebudzynski/apim-portal-mgmt-vnet

APIM: mention mgmt endpoint connectivity for new portal

Author: PRMerger10

articles/api-management/api-management-howto-integrate-internal-vnet-appgateway.md

@@ -182,6 +182,9 @@ After the above command succeeds refer to [DNS Configuration required to access
 
 ## Set-up a custom domain name in API Management
 
+> [!IMPORTANT]
+> The [new developer portal](api-management-howto-developer-portal.md) also requires enabling connectivity to the API Management's management endpoint in addition to the steps below.
+
 ### Step 1
 
 Initialize the following variables with the details of the certificates with private keys for the domains. In this example, we will use `api.contoso.net` and `portal.contoso.net`.