Weird iPhone Issue with N66U: never allows 1 of 4 iPhones to connect

Hi,

Been lurking for a while.
First Thanks to Merlin and this community for their great support.

Now on with the issue. I purchase an eBay iPhone last week. Got all the issues with iOS 7 activation sorted out ... ugh.

Then the weird bit. The phone will connect to either of my 2 2.4g SSID's but it NEVER communicates thru them. Always get a cannot connect to server error. Traffic Manager confirms a few sent packets, and almost 0 replies.

At first I thought it was a bad iPhone. So I fired up a spare N56u I had lying around, and it worked perfectly. It also works perfectly at my in-laws house.

I have rebooted the router, and the phone, as well as fully re-installing iOS a number of times, and a full network reset. No luck. Other iPhones and iPads connect fine to the same SSID. Very weird. Next step is to re-flash or downgrade N66U as it seems to be the issue ...

I am running Merlin 3.0.0.4.374.39_0

Any thoughts ???

Thanks