One channel or everything?
Try another channel and one on-demand title. If only one feed fails, record its exact name and the time. If everything fails, check the app, access status, internet connection and simultaneous stream count.
One device or the network?
Restart the player, check for supported updates and compare a wired connection if available. If you test another device, stop the first stream to stay within your connection limit. Do not change router security settings simply to test playback.
Make one change at a time
Compare a lower resolution or an available alternative server with support. Avoid assuming a VPN will always improve performance. Keep a note of which change helped and contact support if the issue persists.