Thanks Katsushi,
I still seem to be missing something.
I am attempting to use the UserAgent Content Switcher within Pages rather than Posts. Does that matter? Does it only work for Posts?
I just tested it with Posts and it didn’t seem to work either.
See my example below. How much HTML do you need to include between the shortcodes?
[agentsw ua='pc']
<html>
<body>
Page contents here.
</body>
</html>
[/agentsw]