First of all I’d like to say that I’m very new to networking in general but I know quite a bit about mobile networks so forgive me if I don’t understand things straight away 
Basically what I’m trying to do is quite simple, I just want to get an internet connection over LTE.
My problems are currently that I can get the router to connect to LTE just fine, even using carrier aggregation but I can’t access the internet. This problem only occurs on Telekom Germany’s LTE network, their 3G works fine and other LTE networks work fine as well. I of course configured the APN and tested other devices as well. With my phone I can get 60-90 Mbit/s here so the problem has to be something with my config.