I updated the firmware through the web interface and after that I got a 192.168.1.X address but when I tried to access the web interface it doesnt work. Also with different browsers. Chrome says: 102 connection refused. And when I try to access the router through SSH it didn't work either.
I have performed several hard resets by using the 30/30/30 method but I had no luck.
I hope that there are some smart guys who want to help me with this case.