Can't connect to umbrel.local

i have a raspberry pi i have just set it up today can’t find umbrel.local
i have write the login and password “umbrel” on the raspberry and it work but after few hours can’t acces to umbrel.local i reboory my raspberry and try to write the login and password and it doesn’t work i have try all the combinations between the login and password create on the dashboard and everything that i find on the internet does someone have a solutions
and is it normal tha i need to login on my raspberry to acces umbrel.local it’s not mentionned on the installations guide ?
sorry for my english