iPhone 4 update 4.7.2 failed 4 times. Three hour download to phone.

I am having the same problem. I have tried several times, different days, different times of the day and night. Could someone please help us with this? It fails every time.

Try turning off your antivirus and firewall before beginning the update. Especially if you have Kaspersky.

Still no luck. I'm getting very frustrated. I don't have Kaspersky. No antivirus either. Turned off stealth mode in Firewall. Do I have to turn off the whole Firewall for this to work? It transfers data for 5 or 10 minutes before it dies.

Yes, disable your firewall completely. What is your computer and OS? And what type of internet connection do you have (DSL, Cable, etc)

I have DSL, MacBook Pro with the latest Snow Leopard and iPhone 4, Verizon.

I finally solved the problem not by disabling the firewall but by turning off airport and connecting the computer to the router via an ethernet cable. It worked like a charm.

Thank you very much for your input. I will remember the firewall tip if I have problems in the future.

OK, for DSL there is another possibility. Verizon DSL uses the PPPoE protocol, which "steals" 8 bytes from a WiFi packet. The default packet size is 1500 bytes; If you connect via WiFi you need to change the MTU to 1492. You can do thins in Network Preferences on the Ethernet tab. As you fixed the problem by switching to a wired connection this might have been your problem, and it will affect other large downloads also.

Thank you, Lawrence. We use a different wireless but same idea. I changed it as you suggest. We'll see what happens next time I need to download something.