Thanks for the info John, apart from trying more power, I think you're on the right track to 'fill light' at a distance, but there may be better ways if flash is to be the main light source at a distance. This is an area I still have much to learn.
Does the Yongnuo 560 IV just have a single central hot shoe contact?
My Godox TT685N has more (another 3), but I had to buy a specific Nikon version (N suffix), this enables the camera, and EXIF data, to show more info. but only when "all the stars are aligned"
I think the Yongnuo 560 series are not camera brand specific as they don't try to do TTL, so probably only need the one contact. They do have built in decent RF though, which is good.
Cheers, Dave