D4 & WT-5 iPhone/iPad snag

I have had the D4/WT-5 connected to my Iphone 4s and, for a while things worked fine.

Now however I cannot get them to connect, I usually get "Cannot find the server" reponse but occastionally just a camera and a play logo display, with nothing else.

Worse still is the IPad3, which just states I need to connect to the internet! I know it's not the 3G version but it can still see the WT-5 through Settings, Wi-Fi.

Any ideas?

Charlie (UK)