WinHTTP Web Proxy Auto-Discovery Service shows that the Symantec Endpoint Protection's (SEP) Local Proxy Service (LPS) is dependent on that service, when Web Traffic Redirection is enabled.

Microsoft Windows

Symantec Endpoint Protection's Local Proxy Service is dependent upon the IP Helper service, which in turn is dependent on the WinHTTP Auto Proxy Service. If these are not running, then LPS will not be able to start rendering Web Traffic Redirection non-functional. The IP Helper service should be set to the system default of Automatic and WinHTTP Web Proxy Auto-Discovery Services should be a default of Manual, for startup types.