Looking for logging into the Proxy Server Ie 11 User Prompt site and are not getting the correct working link for it? In such a case, you can use the links given here by searching your desired login page in the search box. If the page is present on our website then you will get all the links related to the Proxy Server Ie 11 User Prompt site. After that you can login as usual with your login credentials.
https://social.technet.microsoft.com/Forums/ie/en-US/6ac9ba97-d882-45b0-a839-de7b8d1b5d7a/internet-explorer-11-is-automaticall-sending-proxy-cached-credentials-instead-of-using-the-basic?forum=ieitprocurrentver
https://administrator.de/forum/verhalten-ie11-gespeicherten-proxyserver-passwort-230159.html
http://www.dslreports.com/forum/r19014880-IE-How-to-force-IE-to-offer-login-popup
https://www.techrepublic.com/forums/discussions/proxy-authentication-box-is-not-seen-while-accessing-internet-through-proxy/
https://superuser.com/questions/196343/how-do-i-supply-proxy-authentication-credentials-in-windows-7-or-firefox-3-6
https://superuser.com/questions/479113/windows-security-popup-window-pops-up-each-time-any-connection-is-made
https://stackoverflow.com/questions/35972147/basic-authentication-ie-11-does-not-prompt-for-credentials-chrome-and-ff-do
https://www.cisco.com/c/en/us/support/docs/security/web-security-appliance/118004-troubleshoot-wsa-00.html
https://www.cisco.com/c/en/us/support/docs/security/web-security-appliance/117950-qanda-wsa-00.html
https://community.spiceworks.com/topic/868050-define-ie-proxy-settings-machine-wide
https://www.techwalla.com/articles/how-do-i-change-the-internet-explorer-proxy-settings-from-a-command-prompt
http://woshub.com/configure-internet-explorer-10-and-11-settings-using-gpo-in-windows-server-2012/
https://www.veritas.com/support/en_US/article.100023867.html