Problems connecting a router

[Quercus]

I ahve a problem connecting a new router to Demon Internet.
Can anyone help me?

I get this message in the Routers log.
User name and password authentication failed.

and the diagnositcs give me this
Test the connection to your Internet service provider
Test PPP server connection: PASS
Test authentication with ISP: PASS
Test the assigned IP address: FAIL
Ping default gateway: FAIL
Ping primary Domain Name Server: PASS

The router is a Dynamode R-ADSL-C4-2

I am absolutely sure that the password and user ID are correct.