We are getting an 'Unexpected server error' on the SEPM servers (12.1.4112.4156) where they are trying to download http://securityresponse.symantec.com/avcenter/savlisting.zip.
I'm able to download
The actual SEPM software is trying which has to go through a proxy and I do not see a place for the proxy setup.
Admin page >> Servers >> select your SEPM name under Local Site and select Edit the server properties. Configure the Proxy Server tab as needed
Configuring Symantec Endpoint Protection Manager to connect to a proxy server to access the Internet and download content from Symantec LiveUpdate