Some devices don't like both WiFi bands having the same SSID and turning off the 5Ghz usually overcomes that, although your TV doesn't seem to.
Out of ideas that's why I thought I'd try the new router, otherwise extra wire trailing up the wall
Is there anyway to actually speak to a real person at BT who may be able to assist?
This is an older post. But I'm having the same issue now... I can't work out what's going on. Works with phone, worked with Virgin media. But now Doesn't work with BT