A few things that would be helpful are communications diagnostics tools.
iOS deviecs have to be trying to contact iTunes over a certain port, TCP and/or UDP. What are they?
Can we run a command on the Mac to listen for an iOS reaching out?
If I run:
sudo lsof -i -P | grep -i "listen"
I get:
iTunes 3453 jd 27u IPv4 0xf6f1baead5796d8d 0t0 TCP *:58348 (LISTEN)
iTunes 3453 jd 30u IPv4 0xf6f1baead7836575 0t0 TCP *:3689 (LISTEN)
iTunes 3453 jd 31u IPv6 0xf6f1baeac77577ad 0t0 TCP *:3689 (LISTEN)
Is this correct? Are there any other ports that it might need? (checking to see if I maybe have some other app running on a port thats creating a conflict.. though the fact that its broken on 3 different Macs with comletely different setups makes me doubt this but who knows)
Is there something I can use on the iPhone to test this type of connectivity? Normally I'm pinging something to see that communication works, or telnet on a certain port.
If I run the Fing app, I can ping my Mac. I can scan services and get:
22 ssh
88 kerberos-sec
445 microsoft-ds
548 afp
2002 globe
3689 rendezvous
5900 vnc
I can ping my iPhone from my iMac and it is always successful.
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If I go to my iPhone->General->iTunes Wi-Fi Sync, I usually see "Sync Now" greyed out. Once in a while, it is not. If its available and I click it (when not connected via USB) it says:
Apps
Lookkng for JDiMac...
And about 5 seconds in this will blink for a split second (so fast I had to video tape it to catch it):
Sync will resume when "JDiMac" is
available.
Looking for JDiMac...
Apps
Last Sync: Today at 3:45 PM
Here is some other behavior details:
If I plug into iTunes all my devices show up right away.
When I unplug them, they disappear instantly. Not even a second goes by... as soon as the cable is out, they are gone from iTunes.
For the many months I had Wifi sync actually working, my iMac was hard-wired but my iOS devices were on wifi. I never *had* to have wifi turned on my iMac to sync between them. In fact, I have 2 routers to the Internet and could actually be pointed to one for my default gateway on my iMac, and another for wifi.
To test of course I remove all this complexity, but thats how it used to work.
I've run Cisco, Linksys and Apple routers. It worked with all of these in my environment. If I isolate to just one or the other, it makes no difference.
Thats some of the details and things that I see.