To scale up Web Portal nodes The following post-deployment steps are required if you use an existing Virtual Network during deployment and are required to scale the Web Portal and BI Server nodes.
To add resources on the Azure Marketplace with an existing Virtual Network, you must perform the following post-deployment steps.
Create a custom role with:
"Microsoft.Network/virtualNetworks/subnets/join/action"
"Microsoft.Network/networkSecurityGroups/join/action"
Go to IAM tab under Existing VNet.
Click Add > Add role assignment and assign this custom role to managed Identity.
Click Add > Add role assignment. For For further steps, see the Adding Managed Application Contributor Role section.