Try this. By default the CM4 uses the antenna built into the CM4’s PCB, which is burried deep inside the aluminum case (essentially a faraday cage). You need to tell it to use the antenna cable that you plugged into the CM4.
You might also want to put a little bit of non-conductive space between the antenna and the case. A bit of sugru or double sided foam tape tends to work wonders. Some users have 3D printed plastic antenna mounts.