Hello,
Is the GUP offline (not communicating with SEPM)?
Check this Article:
Troubleshooting the Group Update Provider (GUP) in Symantec Endpoint Protection (SEP)
Is there a proxy on your Network??
Setting up the environment to permit full communication between the SEP client and the GUP remedied issue.
Also, check what version of SEP are you carrying. Hope you are carrying the Latest version of RU7 MP1.
Try editing the LiveUpdate policy.
Under Group Update Provider settings, set the option “Maximum number of simultaneous downloads to clients” to the higher value.
Example:
Hope that helps!!