Azure Cloud Builder 10.9 deploys but fails at the end conf Portal, yet still ultimately works

[ShanonLoughton]

Running ArcGIS Azure Cloud Builder 10.9 downloaded and run as of this post on Azure australia-east (Syd) with an MSDN Enterprise Subscription resulted in an error near I think the end of a single machine, non-HA deployment of 1.5hrs.

Immediately after and without restarting the VM,
- the Portal is either not started or the Azure Application Gateway is misconfigured as I get a 502 Gateway error when trying to access public URL ../portal/home and also ../portal/portaladmin.
- ArcGIS Server works and I can reach ../server/manager, ../server/admin, ../server/rest.

After rebooting, Portal works.

In Cloud Builder deployment log there's a lot of guff around Portal warnings then it seems to work, the last two lines before the last line of error is:

[05/14/2021 18:00:30] [VERBOSE] [xmWebGIS-Pri]:                            [[ArcGIS_Portal]Portal] Waiting for portal to start.
[05/14/2021 18:01:42] [VERBOSE] [xmWebGIS-Pri]:                            [[ArcGIS_Portal]Portal] Portal Site create successful. Was able to retrieve token from Portal.

Then the error that finishes it all is:

Deployment Error:- The deployment encountered the following errors
The resource xmWebGIS-Pri/DSCConfiguration0 of type Microsoft.Compute/virtualMachines/extensions failed. 
 Error:- The resource operation completed with terminal provisioning state 'Failed'.
 <b>VMExtensionProvisioningTimeout</b> - Provisioning of VM extension DSCConfiguration0 has timed out. Extension provisioning has taken too long to complete. The extension did not report a message. More information on troubleshooting is available at https://aka.ms/VMExtensionDSCWindowsTroubleshoot

The https://portal.azure.com/ > Activity Log I see an error inside a "successful" Create Or Update Virtual Machine Extension:

...

which confirms the problem is with resource...

"resourceId": "/subscriptions/857ea8b8-dcbc-401a-9900-c279cd4e2e46/resourcegroups/Test109RG/providers/Microsoft.Compute/virtualMachines/xmWebGIS-Pri/extensions/DSCConfiguration0

What has timed out? What was it waiting for? Is DSCConfiguration0 just the script configuring the whole stack?

More Info
Version  ArcGIS Cloud Builder for Microsoft Azure 10.9.26417
Default Cloud Builder V2 deployment option
Azure MSDN Enterprise Subscription
Region australia-east (Sydney)
Azure Cloud Builder Settings: single machine, non-HA, self-signed cert, all new VNET, RG, Subnets, Storage Accounts, used Storage Accounts > SMB option for Portal Content, enable Azure Monitoring and ArcGIS Enterprise Logs, VM size DS3 v2
@ShaileshGoel  @NikhilShampur