[Pascal_S]

Originally Posted by Brian

The Mac and the iOS device have somehow ended up on different wireless networks. The workaround here would be to double-check each device's connection and switch networks if necessary.

No, I have only one wireless network. And sending the configuration from Mac to iPhone works.

Originally Posted by Brian

The Mac has OS X's built-in Firewall active, and it's preventing OmniFocus for iPhone from sending messages to the Mac. For info on configuring the firewall, look here.

Checked again, it is OK.

Originally Posted by Brian

Little Snitch or some similar application is installed on the Mac and is blocking communication. (Intego NetBarrier is another possibility here; there may be others.)

Never heard of those applications, never installed.

My feeling is that the problems are more linked to Bonjour/networking than to OF itself. So I finally gave up and subscribed to your Beta Sync Server : it works like a charm :-)