If just encounted that errror, that the admin login /admin works, but a user login at / does not work, in the php-fpm-mailcow-1 there is the message that the password for the user is wrong. But even after resetting the password for a new one, the error still persists.
Nginx logs shows a redirect to the passwordpolicy, so it may related?
GET /api/v1/get/passwordpolicy/html HTTP/2.0" 200 20 "https://mail