OK, so this is definitely an issue with the security negotiation on the iPhone 4 and it follows with all iPhones using 4.2.1 in our household.
The network contains two wireless LANs - one for office and one for home. The office uses Time Capsules whereas the home uses an Airport Extreme. Both were set to WPA2 Personal only for security.
I have taken all security off the home network and left the office running with the WPA2 Personal encryption. The iPhone continually states "Unable to join network" for the office, but will join the home network without any security at all.
Since I have no other Wireless routers available, I cannot check to see if WEP or other security protocols work, but this looks more and more as though the security payload in 4.2.1 is either plain broke or has got a bug in it. The MacBook Pro and iPad (using 4.2.1) connect without issue at all to both networks so I know that all is well with the routers etc. Anyone had any ideas with this at all?
I have same problem - My partner and I both have iphone 3G - the only difference is mine is 32 GB and hers is 16 GB.. Both updated to 4.2.1 last weekend - mine has not been able to connect to the router since then. Her phone - no problem and both PCs work fine. Hope someone out there has a thought on this.
A little more now.
Connecting to a DLink router using WPA2 works without issue on both the iPad and the iPhone. Return to the TC or Airport Extreme systems and the iPhones fail.
Now searched through the logs and the issue seems to surround a TKIP failure when the iPhone tries to connect. Since the iPhone cannot be configured for AES this somewhat knackers the diagnosis process any further.
Now the only change to the entire system was the update to IOS 4.2.1 so this really points to a bust up protocol stack in the iPhone. I now have to turn off security and use MAC address filtering to have any degree of security on the WLAN, but this is not good.
Not sure where your problem lies, but no such problem here with my TC using WPA2 Personal for encryption/security with my wireless network.
If you live near an Apple store, you can make an appointment to have a diagnostic check run on your iPhone to rule out a hardware problem. There will be no charge for this.
Hmmm, nearest Apple store is a 140 mile round trip so I will have to plan ahead for that. Still cannot shake the issue that this only reared its head after the 4.2.1 update and only affects the iPhones. Wish it was possible to put the iPhone OS back to 3.x - that would clear this up properly.
How's things in Texas?!
I am wondering whether the length of the key is an issue here. I am currently using a 26 character key. The Apple TV connects, the iPad connects and the MacBook Pro connects as well as the PCs using Windows 7 (yeuch) but the iPhones (all three of them) simply refuse to connect to the secured network. If it was one of them, I could understand it, but all three - and different models - it simply does not make sense. It was also OK before the 4.2.1 upgrade so something's changed somewhere down the line.
I'll keep digging as this is now intriguing me.
Developed same problem with my iPhone 4 (jailbroken), running 4.1.1. Was fine for 6 months, all of a sudden won't connect to my home network, even though 4 other computers, a TV and my wife's iPhone (a 3GS) all do.
Resetting my router (a Verizon Westell 7500) would fix the problem, but only temporarily (e.g., hours at a time).
On my iPhone tried renewing lease, forgetting the network, etc., no joy.
I suspected setting up a Static connection, instead of DHCP, would work, but that would not be satisfying as a solution!
Here's what finally worked for me:
1. Go to your Router's configuration utility. Remove all wireless security (I had been running WPA2 AES).
2. Connect your iPhone to your home network, without the security. Should work. You might also check the settings for IPaddress, router, DNS and Subnet so that you can set up with a Static connection if all else fails.
3. Now "forget" the unsecured network on your iphone
4. Now go back to your router and reapply security as you desire it (recommend WPA2 + AES). Delete and retype the password in the router wireless setup if it is still filled in from before.
5. Go back to iPhone and try to connect again. This worked for me. Note that you may have to reconnect your other home devices, but that's simple.
I'm having the same issue. I use an iPhone 4 (4.2.1), A Time Capsule with WPA2 (10 character password), and extend the range with an Airport Extreme. All my computers connect just fine but this week the iPhone mysteriously stopped authenticating the WPA2. It's mysterious because nothing changed, no updates to either the phone or the router.
I tried resetting the Time Capsule and Airport Extreme to factory defaults and reconfiguring to the same setup as before. Guess what, this worked! ...for about 12 hours then back to broken. ******.
This is surprisingly broad problem. There are at least a dozen threads reporting suspiciously similar behavior. I'm cross-posting this to several in the hopes that it gets some attention.
I'm pretty confident this is a software bug, or bugs, between the Airport and the iPhone.
I have a pretty broad set-up: Time Capsule extended by AP Extreme and a couple AP Expresses, that serve two MacBooks, two iPads, and multiple iPhones.
Yesterday the iPhones stopped connecting to WiFi under any circumstances, even with no wireless encryption--just the iPhones. At every stage of turning off encryption, rebooting various devices, resetting, restoring, ad nausem, +every iPhone I tried failed to connect but all four other Apple devices (MacBook Pro, MacBook Air, iPads) connected easily and consistently+.
Finally, I took down the entire WiFi network, rolled the Time Capsule and Airport Extreme firmware back from 7.5.2 to 7.5.1, and presto, things are suddenly back to where they were the day before, with iPhones happily connecting.
Since this problem predates 7.5.2, I'm guessing that it is open bug that keeps reappearing somewhat randomly whenever Apple updates their firmware.
All that said, I didn't force an update to 7.5.2 yesterday, so the problem must randomly crop up at some point, then is unrecoverable without forcing a firmware change.
Some other threads see this problem even with non-Apple WiFi base stations but again I suspect that it's a similar bug (or interacting bugs) between the iPhone networking stack and the base station code.