Iphone app with LG TV

This one's got me tearing my hair out - just bought an LG tv and installed a wireless dongle, connected it up easily to my home wifi router but have not been able to use the LG tv relote iphone app which refuses to 'find' the tv although both are connected to the same network.

Then I bought the wifi enabled Panny 310 blu ray player and connected it up wirelssly in similar fashion to my home network. The iphone app for this won't 'find' this either - what's the problem here?? am I missing something obvious??

I do have a '3' mifi dongle which I connected up to tv,bd and iphone and both apps work wonderfully so there must be some issue with my home broadband (TalkTalk) - any help would be greatly appreciated.