Thanks for the response. I was thinking that if I could increase the timeout it would still turn itself off if I forgot about it but would be less likely to do so when I was in the middle of watching something streaming over the LAN.
Fundamentally what I want is the box not to turn itself off whilst streaming, so perhaps the ideal would be to register LAN activity as an event it resets the APD timer for then there would be no need to mess with the timeout.