Just finished trying it out. Had a few fits and starts and a fair bit of swearing until I worked out exactly what I was trying to do, but it works fine

.
Like any wireless device, it's easier to set up via ethernet
So it's something in the router...
Main snag I can see is that the laptops can't connect to the AEX and internet at the same time, but I can live with that. If I ever
need to do it, I can use ethernet cable to connect them- a quick test shows that seems to work OK.
Reasonably happy bunny now, thanks again