Network issues can sometimes stall your services making watching TV an unpleasant experience.
Check your Wi-Fi quality
Go to Settings -> Info & Diagnostics -> General Diagnostics. If the Quality is above 60% then it is OK. If it is lower, you can try to improve your Wi-Fi network coverage.
Check your Broadband speed
Check you Broadband speed by logging onto your Internet Service Provider website
Check other On Demand services
Try using other On Demand apps. If other services are working fine, there may be a temporary problem with the On Demand app you're trying to use.
Try rebooting your router, then your device
Try switching off by unplugging your device from the mains. Wait 30 seconds before plugging it back in and switching on again.
Still not working? Try doing the same with your Internet router.