The Symantec Endpoint Protection (SEP) for Mac client, when using the Web Traffic Redirection (WTR) feature, may interfere with the loading of some captive portals.
macOS 10.13.x and 10.14.x
The SEP for Mac local proxy service (SymSepLps) will now route captive portal authentication requests DIRECT. This issue is fixed in Symantec Endpoint Protection 14.2 RU1 MP1. For information on how to obtain the latest build of Symantec Endpoint Protection, see Download the latest version of Symantec software here.