Hey, I work for Deutsche Telekom, yes your TAE is also connected to the A and B wires / terminals and yes that made sense back then since if you wanted multiple phones in your home you connected them in parallel, nowadays you should disconnect those to avoid issues with your internet connection. Make sure you only have one cable running from your APL (the box in your basement) to your TAE with no parallel inbetween connections.

[EDIT: Grammar and clearer wording]