Ok. Are you using "admin" as username?. If no, have you tried changing router's admin user to "admin"?. There's a bug if using other usernames with buggy behavior on iptv.
Can you track down which specific component has issue with a different username? I know that a few such cases were fixed years ago, there might still be some service that will expect the superuser to be "admin". Those are usually easy to fix, as long I know which service is affected.