no internet access

Hello!

I have a problem with my internet connection since 5 days ago (Router Homebox 6441). All lamps in the router is green (normal) and I have checked to 192.168.1.1 for many times, the online status is verbunden (connected). I have tried to reset the router several times, and there was no change at all, still no internet access (yellow triangle sign in the right corner of my screen).

Also, I have tried to call the customer service as suggested by o2 officers in my city, but I did not understand what did they mean. Could you please help me to overcome this problem asap? 

My code area is 24118.

My Kundennummer is DE16549774.

Thanks!