In the TV manual it odes state that 'If pure High-throughput (Greenfield 802.11n mode is selected and the encryption type is set to WEP or TKIP for your wireless router, Samsung will not support a connection in compliance with new WiFi certification specifications' I do not know what this means or how to find out what encryption type I have! Sorry...
I have found that the encryption on the router is AES
I have also just found a footnote in the TV manual that says it doen't support a network connection if the sepeed is less than 10Mbs... I have 1.7!! Sorry to have wasted your time.