Looking for logging into the Ad User Unable To 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 Ad User Unable To site. After that you can login as usual with your login credentials.
https://community.spiceworks.com/topic/291929-users-unable-to-logon-to-the-domain
https://social.technet.microsoft.com/Forums/office/en-US/3ddd8864-2524-41d1-a5be-e8ced1c88ef5/active-directory-user-unable-to-login-to-sharepoint-2010?forum=sharepointadminprevious
https://community.centrify.com/t5/Centrify-Express/AD-user-account-unable-to-log-into-machine/td-p/32027
https://pubs.vmware.com/log-insight-15/topic/com.vmware.log-insight.administration.doc/GUID-C1F5B275-C220-4EDC-9B61-7218588DA75B.html
https://sharepoint.stackexchange.com/questions/187953/user-cannot-login-after-changing-ad-properties
https://serverfault.com/questions/399827/unable-to-login-with-a-domain-account
https://www.jamf.com/jamf-nation/discussions/2202/client-can-t-log-in-to-ad-bound-macs
https://forums.tomshardware.com/faq/one-domain-user-account-cannot-log-on-to-domain-from-one-particular-computer.1634151/
https://www.c5insight.com/Resources/Blog/tabid/148/entryid/275/sharepoint-login-issues-how-to-fix-users-who-cant-log-in-via-their-user-principle-name-upn.aspx
https://kb.tableau.com/articles/issue/active-directory-users-unable-to-sign-in
https://centrify.force.com/support/Article/KB-3000-Troubleshooting-login-issues-on-Mac-systems/
https://success.trendmicro.com/solution/1120296-unable-to-authenticate-due-to-a-user-error-message-appears-when-logging-in-using-domain-credent
https://confluence.atlassian.com/confkb/user-management-and-login-issues-troubleshooting-180847174.html