First off all, i dont know if its the router (its a very good one, fritzbox 7590) or the deco that crashes. Im downloading at my full speed and then it stops downloading and i cant enter the deco app etc. i need to take it out of the power cycle anmd tthen i need to enter the app (internet still doesnt work) and restart the deco. Its really annoying, while it crashes the deco light stays green and then when i disconnected it goes red blink. (how it should be)

What can i do against it?

Btw what setup would be the best: Fritzbox router and deco ip clients (then i can connect them trough lan to the router) or reverse way?

My setup looks like this: Deco A connected with lan cable to a rj45 plug, goes to the router (fritzbox)but in the app it says its coupled with the Deco B?), Deco B (MAIN) connected to router via RJ45 plug, Deco C connected to Deco B (wireless or powerline, idk)