iPhone connection to WiFi

Hi,
I've got a problem with my WifI and been unable to sort it out.

My equipment:
Netgear DG8343UK hard wired modem/router, connected to an Airport Express via ethernet cable.

I set the Airport Express up (using Airport Utility) to function as a wireless network and at the end of the process after an error warning, a message appeared to tell me that settings had been changed from DHCP & NAT to bridge mode, because the Netgear modem/router was using NAT to provide private IP addresses.

Problem:
I get a signal from the airport Express, but when I try to connect to it using my iPhone 4 (running OS 6.1.3) and put my password in, I get the error message:
'Unable to join the network ***'

My wife is able to connect to the signal on her iPad and my daughter is able to connect with her Macbook, so I know Airport Express is working -it just doesn't work with my phone.

What I've tried already:

On the router:
Disconnecting and starting it up again

On the Airport Express:
Disconnecting and starting it up again
Renaming the wireless network name
Changing the security between WPA/WP2 personal and WPA2 personal

On the iPhone:
Switched off the phone and then switched it on again.
Switched off WiFi and then switched it on again
Switched off cellular data and then reset network settings


Have any of you peeps come across this problem and solved it, or got any suggestions?

Have you tried THIS

In reply to a post by time2die:

Have you tried THIS

Yes I have, although this applies to iPhones running IOS5 rather than IOS6.
-It didn't have any effect.
The situation is weird, because I know the phone and Airport Express are talking to each other, inasmuch as if I put the wrong password in, I get the message 'incorrect password' rather than the 'unable to connect' message.

Thanks for the suggestion anyway.

Is mac filtering set?

No it's not, which is why there is no problem with the Macbook and iPad connecting.
I used Airport Utility to set it up and just expected that ALL the Apple products would work, not just two of them

I know I'm replying to my own post, but it's to add extra information.

One last thing....following a suggestion in a technology column of a newspaper, I removed the password setting on the Airport Extreme, to see if the iPhone would connect up then and it does.

I then went back into the settings on Airport Express and setup a password restriction again, only to find that when I tried to connect from the iPhone again (and put in the password) I got the 'Unable to connect" message.

Why would this be?

Are you using WEP?

Are all your various bits of firmware up to date? Some Apple stuff had issue with AES encryption that needed a patch, iirc.

Yes I've updated everything to the current firmware (Airport Express/iPhone/Router).
- I think this is where I went wrong I shouldn't have updated the iPhone's operating software; it worked fine in its earlier releases

Hi,
The two options for security when using Airport Express are:
1/ WPA/WPA2 Personal
2/ WPA2 personal
I've tried both, but with no success.
The iPhone gives the message 'Incorrect Password' if I type the wrong one onto the iPhone, but if I type if correctly I get 'Unable to join the network'
It's a lose - lose situation.