You need to understand the current networking situation in your car.
All canbus comminucations incl LIN for the generator/BDM are handled by the extenal canbus gateway that lives below your right hand side tweeter.
The BCM only has a comfort canbus line to it, now.
Powertrain CAN goes to the gateway
Diagnostics CAN goes to the gateway
Instrument cluster CAN goes to the gateway
In the 7e0 BCM (and any other non-088 PQ25 BCM), the BCM is also the canbus gateway.
So the external gateway is now obsolete and must be removed.
All CAN wires and generator LIN must be re-routed to the BCM since that's where the virtual gateway resides from that moment on.