If they are then, you may have to work on these articles below:

Symantec Endpoint Protection Manager 12.1 Communication Troubleshooting

http://www.symantec.com/docs/TECH160964

Symantec Endpoint Protection: LiveUpdate Troubleshooting Flowchart

http://www.symantec.com/docs/TECH95790

can you pass on the sylink log?

I have attached the sylink log files from two clients that are experiencing problems.

The file 'Client non proxy updates from server' is the client that has the error

Downloaded new content update from the management server failed. 

from the client log which is not updated, it is in process for downloading the ddefinition.

didn't the client update?

can you collect for longer time?

Hi,

Can you please check your proxy configuration its block any limitation

or

check your network firwall also.

Thanks for the help so far.

I have attached a new sylink file from the server that isn’t downloading updates from the management server. 

On this particular machine, the firewall is disabled, and allowing all communication through. I have also explicitly defined in the live update policy to not go through a proxy, and connect directly to the server. I can navigate to the zip file that it is trying to download it using ie and it can download just fine. Most other clients don’t seem to have an issue in downloading the updates either.

In regards to the clients which are downloading their updates from the internet, the machine that I was collecting logs for decided to start working. I am currently collecting logs from another machine that is experiencing the same issue. This machine does not have a firewall enabled (the rules are set to allow everything), and it is configured to go through a proxy. This machine is using the same proxy as other clients which do not have issues in updating. Its dns and gateway setting are the same as other funtioning clients too. 

I am currently collecing sylink logs for this machine now. Maybe by the process of observing it in action will cause it to behave differently and work. 

Many Thanks,

Sam.

I think some of my misbehaving clients are bound to the Heisenberg uncertainty principle. As soon as I start collecting logs, they start to work. However they are only the clients which download updates from the internet and not the management server. I will go though these clients one by one and get them to start logging and they should come in line.

However not eveything is so rosy. Some of my clients that are getting updates from the management server are still failing with the errors stated above. Again, most clients are working fine, just some of them fail to update.