Such a great technology, but it can be very flaky. And when it's not working, sometimes nothing but a complete reinstall of both the OS and FMS will do. But I do hope they continue to include and update this great technology -- I'd hate to have to hire a PHP programmer to reconstruct the many screens that are handled by IWP.
(Note that I have latest OS X, FMS 12, plenty of RAM, etc. Others have reported the same setup with no issues, so I'm going to call this a "flakey" issue.)
With well over 30 separate FMS installs throughout the years (I think I started with Server 3, and once dabbled with a Linux install), every single one since Server 7 installed smoothly and ran without incident when using FileMaker as a client.
But when IWP starts to complain, good luck with trouble-shooting. Portal alignments? RAM? FMS - OS - Apache? Plug-ins? Sunspots?
Tonight will be a complete wipe and reinstall of the OS and FMS.