Given your building’s history and restrictions....
It’s been an issue since I bought the building last year and we still haven’t found an acceptable work around.
ALL electrical and networking wires are foamed in place. This has caused problems for us as we can't upgrade anything.
Have you given thought to setting up a Mesh Network? It’s a solution for the audio side (and has broader application if you want it to).
Run a short length of ethernet cable from the Mesh Network Satellite to your K40.
The K40 was one of the options I was considering. It’s a great unit. I have a feeling it’s potential is being hobbled by your current setup.
You can still use the ENO filter after the Satellite, should you want to and should it add to overall performance.