I have 4 computers connected to a Wifi router (with no Internet uplink). Whenever we enter the Network interface for Audio/Midi preferences in ANY of the computers, the Mac beachballs and then finally finds its way. Occasionally, however, one of the computers fails to receive the MIDI information that was destined for it via the Network MIDI interface.

Changing to all wired connections does NOT help.

Adding Internet uplink DOES help and the problem is resolved. This makes no sense to me as the computers can access each other just fine with or without the Internet uplink.

Any ideas?

[NOTE: I'll update the question if people correct my terminology, or feel free to do that if you have the rights].