Is it possible you could try testing with your phone data as a hot spot?
Head onto live chat to report the fault. Just make sure to click "chat online".
You could also send an email to customer support with videos/pictures if you think it will help, address in the below picture.
How hot to the touch is the stick?
@gavs82008 it doesn’t appear to be a WiFi issue as I tried my phone data. It’s let me watch 45 minutes of a film on Netflix through the stick, but won’t let me watch more than 5 minutes of the channel 4 app. I’m going to try the live chat…thanks for the link