Serius problems with internet connection

Hello, I will have to write in English since my german is not so gut...

In the last 3-4 months I experience serius problems with my internet connection and it's just getting worst!!

I work on line so that is a very serious issue for me. Every 10-15 minutes the internet connection breaks and for the next 5-6 minutes it starts and it stops 5-6 times!!! I am going crazy here!!

Maybe I have an old hardware I don't know. I have it since 2011 and it is a AVM Fritzbox FON WLAN 7270

Can someone give me a solution?

Thank you in advance for your time