I think I have solved it myself. I had the T110 switch mounted on the gate post only about 180mm off the ground. I have raised it up to 680mm above ground, and now the signal strength is showing...

I have a T110 switch outdoors on a gate, and the H100 hub indoors. Between them is 12 meters distance, and one single-brick wall. This seems to be too much for the signal? The setup was easy to get...