Downstream server unable to connect to upstream server: "request failed with HTTP status 503"

[capt...@gmail.com]

This is my 10th downstream server that I've installed for my Org. Been running WSUS for 2 years now. There are downstream servers in each of our network environments that get their updates from a single upstream source. I am attempting to put in place this new downstream server but am running in to difficulties.

virtualized Windows Server 2019OS
8 gig ram
IIS config changes:
Queue Length set to "25000"
CPU>Limit Interval set to "15"
Rapid-Fail Protection>"Service Unavailable" set to "TcpLevel"
Recycling>Private Memory Limit set to "0"

This is an initial setup and trying to get that initial connection to host. Also, this is a DMZ network vlan so there is no connectivity to WAN. I am able to telnet to upstream server via port 8530. SSL is not configured. Log snip is below.

Does port 8530 need to be open both ways? It isn't for my other downstream servers. Port is only open towards the upstream server and has been this way for 2 years now.

I've deleted the "wsus Administration" web site and re-ran the postinstall command. No good. I am now working on a brand new server\setup and still am not connecting.

Thanks!!

2020-03-03 17:56:48.916 UTC Error WsusService.3 UpdateServicesRollup.DoRollup Failed to rollup DSS information. Exception=System.Net.WebException: The request failed with HTTP status 503: Service Unavailable.
at Microsoft.UpdateServices.Internal.Reporting.Rollup.UpdateServicesRollup.GetRollupConfiguration()
at Microsoft.UpdateServices.Internal.Reporting.Rollup.UpdateServicesRollup.SynchronizeConfiguration()
at Microsoft.UpdateServices.Internal.Reporting.Rollup.UpdateServicesRollup.DoRollup(). Rollup terminated.
at Microsoft.UpdateServices.Internal.Reporting.Rollup.UpdateServicesRollup.DoRollup()
at Microsoft.UpdateServices.Internal.Reporting.Rollup.RollupAgent.WakeUpWorkerThreadProc()
at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Threading.ThreadHelper.ThreadStart()
2020-03-03 17:57:10.379 UTC Info w3wp.115 ThreadEntry TimerQueue.FireNextTimers
2020-03-03 17:57:10.379 UTC Info w3wp.115 ServerImplementation.UpdateCache Database change occured; check if we need to update cache.