Microsoft Edge prompts for authentication credentials when connecting to an internal proxy using NTLM authentication through the Symantec Endpoint Protection (SEP) client Web Traffic Redirection feature.
Microsoft Edge browser does not support proxy authentication over localhost.
Use one of the following to work around this limitation of the Microsoft Edge browser:
Use an alternate browser that does not block NTLM authentication over localhost
Use an alternate proxy authentication method for the affected client(s)
Disable Web Traffic Redirection and specify the proxy using another method