Our internet connection(Magenta M) drops repeatedly. It has been five days. I checked the router and follow the procedure fritzbox suggested. However, it didn't help. There seems to be no problem with the router. Chat bot in telekom restarted connection line several times and it works for few minutes. Later, it just drops sporadically. 

last year, when the similar problem appears, there was a loose connection at the main board in the Keller in our building.