End-users are presented with the Roaming Captive Portal page from Web Security Service (WSS). This only impacts those machines which have an Integrations policy configured for seamless identification with a pre-14.2 Symantec Endpoint Protection (SEP) client installed.
Symantec Endpoint Protection prior to 14.
SEP clients prior to 14.2 do not support seamless identification.
Upgrade SEP to 14.2, or greater. For more information, refer to Best practices for Endpoint Protection and Web Security Services integration and Symantec™ Endpoint Protection 14.2 Release Notes.