Description: The Error means The connection with the server has been terminated.
If you check out the C:\Windows\system32\LogFiles\HTTPERR\httperr*.log files on the distribution server, you'll likely see either Timer_MinBytesPerSecond errors or Timer_ConnectionIdle errors. These are caused by IIS' default settings, contained within its metabase, which define the minimum traffic flow rate for a connection to be kept alive and the maximum idle time allowed before a connection is dropped. For some reason, SUS servers seem to take their good old time while downloading updates, and these parameters are exceeded and the distribution server drops 'em.
1) From IIS Manager, right click on the Internet Information Server (IIS) Manager root level folder and go to Properties. Check the box to enable direct metabase editing. Click OK.
2) Open the C:\Windows\system32\inetsrv\Me-taBase.xml file in Notepad. Do a search for "MinFileBytesPerSec". Change the setting for MinFileBytesPerSec from 240 to 0. Do another search, this time for "ConnectionTimeout" to be 600. Save changes and exit.
3) Restart the IIS Admin service to effect the changes.