I have a Netgear WNDR3800 router and I use WPA2 encryption for WiFi. I have two iPhones (4 and 4S) that are experiencing the same problem. Both running 5.1.1 version of iOS (I know its older then current).

The problem is that both iPhones experiences intermittent problems with WiFi connection while all other WiFi devices work perfectly fine. Both iPhone indicate that they are connected however I there is no internet access. If I manually disconnect and try to connect it doesn't connect any more. Forgetting the network and connecting again doesn't help either. Only if I restart the router, both iphones are able to connect and surf the internet.

note, meanwhile all other devices Android tablet, Windows and Mac laptops work and connect to WiFi just fine (wired Ethernet also works). Also, same iphone(s) work fine on other networks like in my office at work.

Things that I've tried: 1. reset router setting to default and update router. 2. forget wifi networks on iphone and try to reconnect. 3. change the DNS to google DNS on iphone. 4. restart the iphone(s) 5. I was suspecting interference, so I changed my router to transmit on a less busy channel.

Here is a similar problem: link However the solution doesn't apply because I have only one DNS set.

Here is one thing that I have yet to try: "Reset network settings by tapping Settings > General > Reset > Reset Network Settings." source.

this link is also somewhat similar. However, I tried setting Google DNS on my iPhone and it didnt help. Maybe I should try to set it in my router configuration.

Edit2: I think its important to point out that both iPhones worked fine with the same router in the past.

Any help/hints/suggestions are welcome! I'm getting pretty desperate.