Hello Pixxotta,
first, have you changed the default password using telnet or via plug-in?
(If not, its recommended or else when you login the web-interface its the default password "Dreambox")
To set a password go to:
1) Main Menu -> Plugins -> Web inteface
2) Press Yellow button to go into interfaces (color might vary depending on image)
3) You should see a list of ip address/port/ssl/Authorization/disabled
select the one matching your ip of Dreambox and press Yellow button to change! (if nothing, press red button to add a line)
4) In the Edit Interface you will see:
a) Disabled [do not allow webinterface to work]
b) Address [if set to 0.0.0.0, change to the ip address of the dreambox]
BUT you wont be able to stream!!!, there is a problem when interface ip is not 0.0.0.0 and if it has a password!!!
c) Port [80 default]
d) Require Authorization [Put To Yes to enable password Protected]
5) Press green for ok -> exit from menu
6) login too webinterface and you should be prompted with a user and password.
User: Root
Password: what ever you put (telnet) or Default (Dreambox)
There are other ways to make the web interface more secure but this is the easiest way for now!
Cheers!