From the photos in this post, it looks like the antenna is a discrete unit (good) hanging at the end of a piece of coax.
What’s the possibility/ advisability of cracking the housing and pulling the antenna outside, so that it dangles inside the switchbox? Might help some of the signal strength issues if it were isolated from the board a bit more, at least that’s my thought…
Before even trying that, it would seem like the easiest test would be the antenna connector- it’s possible that it isnt properly seated, which would lead to poor performance. How easy is it to get at this connection?