Nice link! And, aha!, I guess just soldering two solid 8.6 cm wires to a RFM95W, one on top of the board and another on the bottom to a single antenna connection, doesn't make a dipole antenna, lacking any "transmission line" as shown in an image from that link:
That probably makes the following orange and white vertical wires attached to a RFM95W in my single channel gateway a bad solution then:
