Well, I’m not sure what’s going on. Today I downloaded the beta you suggested, connected to the Mango, but before uploading the image I tried Wireguard again.
Despite it not being able to connect yesterday, and remaining powered on the whole time, today it connected perfectly.
Grrrrrr. I have worked in both software support and development, which is why I really do hate things like this. Trying to track down an issue when it didn’t work, nothing was changed, and then it did work.