DNS server not responding

My internet does not work. It says DNS server not responding. After that I checked the fritz box and the message that appears in fritz.box is"access denied for " and then my user name with the @s92.bii-o2.de email... Like if my user was not working anymore ..

I just started my contract in less than a month, so I do not understand what can be ..
I alredy checked all the cables and even try a router from a colleague, but the error remains the same, so it does not seem like a problem for the router.