Problems synchronizing WSUS downstream servers

I have set up a WSUS hierarchy consisting of an upstream server, and five downstream servers.
The problem is that three of the downstream servers will not synchronize to the upstream server. They get the status Failed. With the following details:
WebException: The operation has timed out.
at System.Net.ConnectStream.Read(Byte[] buffer, Int32 offset, Int32 size)
   at Microsoft.UpdateServices.ServerSync.ServerSyncCompressionProxy.GetWebResponse(WebRequest webRequest)
   at System.Web.Services.Protocols.SoapHttpClientProtocol.Invoke(String methodName, Object[] parameters)
   at Microsoft.UpdateServices.ServerSyncWebServices.ServerSync.ServerSyncProxy.GetUpdateData(Cookie cookie, UpdateIdentity[] updateIds)
   at Microsoft.UpdateServices.ServerSync.CatalogSyncAgentCore.WebserviceGetUpdateData(UpdateIdentity[] updateIds, List`1 allMetadata, List`1 allFileUrls, Boolean isForConfig)
   at Microsoft.UpdateServices.ServerSync.CatalogSyncAgentCore.GetUpdateDataInChunksAndImport(List`1 neededUpdates, List`1 allMetadata, List`1 allFileUrls, Boolean isConfigData)
   at Microsoft.UpdateServices.ServerSync.CatalogSyncAgentCore.ExecuteSyncProtocol(Boolean allowRedirect)
I addition, Event ID 10022 in the application log.
When synchronizing to Microsoft they work fine, but not to the upstream server.

I would be most thankful if someone could advice me on this one, making all downstream server synchronize.

Kind regards
Jan B.
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Are they all going across the same router?
Firewall issues?

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FulfilmentAuthor Commented:
Thanks a lot for the effort. The problem was to some degree located in the firewall. In fact the problem was solved by adding port 8530 to the Default Web page in IIS at the upstream server. It was originally set up to sync on port 80, which is routed directly to our web server. I wasn't aware of that.
Cool. Frustration is over then :o)
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FulfilmentAuthor Commented:
Solution made us look at the right place.
FulfilmentAuthor Commented:
Sure! Thanks. Hope I did right regarding to the points.
Absolutely. thanks a lot.
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Microsoft IIS Web Server

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