I am trying to download iOS 5.1 on my iPhone and iPad. Both times it tries connecting to the software update server and just hangs there. I've tried doing both over wifi and get error message. What do I do?

Question

I cannot download the ios 5.1. I'v tried doing it through itunes after downloading the latest itunes. It says that my phone and ipad both have new updates and tries to coonect to update software server. That is where it hangs up and just keeps trying to connect but never does. Then when I try to update my devices over wifi, it tries and thens gives me a download failed message after a few minutes. What do I do?

Answer 1

This has solved loads of people who have this issue and have used an alternate DNS setting.  Below are instructions for both iPhone OTA and on you Mac
If you are getting the error message "Unable to check for update" when you try an OTA (over the air update)
Change DNS Servers
Settings -> Wi-Fi
Click the blue arrow on your connected network
Delete everything in DNS and replace it with 208.67.222.222, 208.67.220.220
Try again
If this works, you will probably want to remove the WiFi network using "Forget This Network" and then reconnect to it to get your original DNS servers back. Alternatively, make a note of the original DNS servers before deleting them and replace it after you are done.
If you are getting the error message "Unable to check for update" when you try through iTunes
On your Mac
Choose Apple menu > System Preferences, and then click Network.
Select the network connection service you want to use (such as Wi-Fi or Ethernet, unless you named it something else) from the list, and then click Advanced.
Click DNS, and then click Add at the bottom of the DNS Servers list. Enter the IPv4 address for the DNS server.
You can use OpenDNS
208.67.222.222
208.67.220.220
or
You can Google Public DNS if you want
8.8.8.8
8.8.4.4
I have actually repointed my routers DNS so all my devices now point to OpenDNS servers