iPad not connecting to our WIFI, very odd symptoms!

We have an issue with our first generation iPad mini. Recently it has decided to stop being able to connect to our WIFI network which is secured with standard WPA-PSK / AES encryption. It was all working fine before, and to the best of my knowledge nothing had changed. What is really odd is that our other devices connect to our WIFI fine, (iPhone 5 and 4 and MacBook Pro). And the iPad connects fine to other wifi networks, (Waitrose cafe and personal hotspot on my iPhone 5). The router is the TP-LINK TL-WR1043ND connected to our Virgin Media Super Hub, which I have upgraded to the latest firmware "3.13.15 Build 140319 Rel.41339n" since the issue, which has not fixed the issue. The iPad was on 8.2.? at the time of the issue and has now been upgraded to 8.3 which made no change to the issue.

What actually happens is that when I try to connect to the network and put in the password it comes up saying ' Incorrect password for "My Network" '. I know I have the correct password as I have tried it many times and also forgot and connected to the network on other devices just fine. The other test I do is to temporarily remove all wifi security, then it just says ' Cannot connect to network '.

At one point it was connecting to the router, if I didn't have the WAN connected, i.e. connecting to the router with no internet. But now it isn't???

I have also tried since the OS upgrade on the iPad, network reset, all settings reset and factory reset, neither made any difference.

I am at a loss to what the problem could be, other than a hardware issue, but if so why can it connect to other networks?

Any ideas would be greatly appreciated

Cheers,

Tim.