WSUS Server not synchronising anymore

Hello,

I am on a windows 2008 server with WSUS 3.2.7600.226.

Since some time the server is not syncronising anymore. It fails with error type unknown : it fails with the following exception:

IOException: Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host.

---> System.Net.Sockets.SocketException: An existing connection was forcibly closed by the remote host
        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)

In the event viewer all we get is : The last catalog synchronization attempt was unsuccessful.

I already reinstalled WSUS with a new database and new IIS web site.

Please assist as to how to solve this problem.