Buxbusters iPhone WiFi Sync Battery Drainage Bug Solution
Problem :
The iPhone 4S has been plagued by battery drainage issues since its launch together with IOS 5. This solution will only deal with the so called WiFi sync configuration bug : if an iPhone 4S would be used together with iTunes and the WiFi sync function would be enabled, the battery would drain very fast when idling : the battery would typically drain 30 percent when idling for 8 hours and show several hours of so called 'phantom' usage. These are rough numbers. During the testing sometimes the phone could be configured in such a way that the drainage could be about 10 percent/hour(!) Normal drainage overnight with a fully charge iPhone typically stays within 8 percent in about 10 hours.
There are still more problems as reported by users that have nothing to do with the WiFi sync configuration bug, but they are not reproducable by me : if you own one of these plagued devices and would like to help solving the issue, please contact me so I can help.
Cause :
(NON technical explanation )
Some routers don't properly communicate with the iPhone. The iPhone tries to communicate but fails and keeps trying : the WiFi sync bug is born.
(technical explanation )
The iPhone uses something called multicast DNS - this feature is part of Apple's bonjour networking. Normally there is no problem with this, but some routers are not communicating properly with the iphone 4S. Everytime you connect to a WiFi network, the router not only gives you a unique address ( IP ) but populates the DNS entry in your iPhone : this DNS is needed to resolve website names to IP's. Without it you would not be able to use names to point to something on the web.
Some routers use something called DNS forwarding - they act as a DNS server within the WiFI network and forward all traffic regarding DNS queries to the proper DNS servers ( Typically outside the WiFi network ). Some routers who act as DNS forwarders aren't doing this properly : the iPhone 4S continuously tries to resolve a name using multicast DNS but keeps failing to do so because the router won't comply. These retries are causing the excessive battery drain : the iPhone won't go to sleep when it is supposed to and stays awake.
Solution :
Find your DNS entry for you WiFi network and check to see if this holds a valid IP for a DNS. If it only shows your router's IP you have the chance of the WiFi drainage bug showing up. Either configure your router in another way so it uses a proper DNS or change the DNS entry in your iPhone to something else ( For instance the Google Public DNS : 8.8.8.8 and 8.8.4.4 : they both can be added in your iPhone by using a comma 8.8.8.8,8.8.4.4 ). Remember : everytime you reset your phone your router will populate this field again with it's DNS so you have to redo the action.
