Why doesn't Plesk Onyx 17.8.11 let me into the admin panel at the usual address?

Question

Plesk

Created a server on Amazon Lightsail.
The server was immediately created with the Plesk Onyx 17.8.11 administration panel installed.
I generated the first login page, entered the admin name, password, mail. Login admin.
But there was a problem, now in order to enter the admin panel of the panel, you must always generate a secret address for logging in via SSH.
At the usual address https://IP.IP.IP.IP:8443/ , the authorization form opens, but does not let it in, swearing at the username and password. There is a user in the admin panel itself, but even when requesting password recovery, it swears that there is no user.
Sysadmins, has anyone encountered such a problem, help?
Server set up for the first time.