DirectoryEntry myLdapConnection = new DirectoryEntry("LDAPS://ldap.abcd.net:636/", "uid=hris,ou=People,dc=testbd,dc=net", "abc123");

         DirectorySearcher search = new DirectorySearcher(myLdapConnection) { Filter = ("(objectClass=*)") };
         search.CacheResults = true;
         SearchResultCollection allResults = search.FindAll(); //Getting "Unknown error (0x80005000)"

DirectoryEntry nRoot = new DirectoryEntry("LDAPS://ldap.abcd.net:636/ou=People,dc=testbd,dc=net");
        nRoot.AuthenticationType = AuthenticationTypes.None;
        nRoot.Username = "uid=hris,ou=Group,dc=testbd,dc=net";  //full dn

        nRoot.Password = "abc123";

        DirectorySearcher nDS = new DirectorySearcher(nRoot);
        nDS.SearchScope = SearchScope.Subtree;
        nDS.Filter = "objectClass=*";

        SearchResult sr = nDS.FindOne();// Getting ""Unknown error (0x80005000)"