Try this as a next step.
Disconnect the duponts from D1 mini. You can leave the wires “hanging”.
First try to establish a working passthrough that doesn’t involve the esp at all. Eg it should simply be passing through to the wires between the handset and controller (a bit like an extension cord)
Check that the order of your wires of your sacrificed ethernet cable “run straight through”.
Your first goal is to insert this rig which just retains original hanset functionality and behaviour, without esp involved at all…
