Reseller configured parameter "External Login URL" according to the instructions, but it does not work for customers.
"External Login URL" does not work properly for reseller due to the software issue #POA-111638 "External Login URL not working as expected for reseller customers". Such functionality is only available for customers of Provider.
The fix is planned to be included in one of the future product updates.
Contact your Technical Account Manager or PTA team (firstname.lastname@example.org) in order to clarify the status of the issue.