Just for anyone else trying to troubleshoot this and it's not firewall related try the following I got from support.
Please perform the test mentioned in the following link to see if the SEP client is communication with the SEP Manager.
http://service1.symantec.com/SUPPORT/ent-security.nsf/docid/2007101711140148
Note: The test needs to be run on the client.
If the test fails, please follow the below steps:
1. Login to Symantec Endpoint Protection Manager (SEPM)
2. On the left side, click on Clients
3. Highlight the Group where Clients are reporting and then, click on the “Details” tab
4. Note the Policy No. (1st 4 characters)
5. Browse to the SEPM installed location i.e.
C:\Program files\Symantec\Symantec Endpoint Protection Manager\data\outbox\agent\
6. Open the foldername which begins with the above noted Policy No. (1st 4 characters)
7. Copy the Sylink.xml file from the above mentioned folder to the client computer's Desktop for now
8. On the Client machine, Click Start > Run and type: "smc -stop" (without quotes) and click OK
9. Copy the “Sylink.xml” in to the SEP Client install folder (default location is C:\Program Files\Symantec\Symantec Endpoint Protection. It may differ to C:\Program Files\Symantec Antivirus, if upgraded from SAV-CE)
10. Agree to over-write the existing file
11. Click Start > Run and type: "smc -start" (without quotes) and click OK