Following an upgrade of Symantec Endpoint Protection Manager to version 14.3 MP1 the default home page URL under Virus and Spyware Protection Policy>Miscellaneous>Internet Browser Protection is shown as http://www.symantec.com/enterprise/security_response/index.jsp.
This URL is no longer valid.
To resolve this issue change the URL to https://www.broadcom.com/support/security-center.
Alternately creating a new policy will also result in the URL being corrected.