Here's a satellite parameter that affects signal-to-noise ratio. DVB-S2 roll-off factors (0.35, 0.25, 0.20, 0.15) affect bandwidth and SNR. Your IPTV Reseller Panel must match the roll-off. The IPTV Reseller Panel you need must auto-detect roll-off. Most panels assume 0.35, losing SNR on newer transponders.
The pattern that keeps showing up is that British IPTV satellite channels from newer transponders have lower SNR on your panel. Your panel's roll-off assumption is wrong. Your IPTV Reseller Panel either auto-detects roll-off or loses SNR.
What actually works is roll-off auto-detection. A good IPTV Reseller Panel detects the roll-off factor from the signal. Your British IPTV service can receive any transponder at optimal SNR. Without detection, you're using wrong settings.
Imagine a British IPTV transponder uses 0.15 roll-off. Your panel assumes 0.35. It wastes bandwidth and SNR drops 2dB. A panel with auto-detection would use 0.15. Your panel's assumption costs signal quality.
One sentence: roll-off isn't universal. Your British IPTV panel either detects it or guesses wrong.