Bass below a certain frequency (e.g., 80Hz) should go to the subwoofer. That's the crossover. Some resellers implement proper crossover. Most send full-range audio and let your receiver handle it.
Here's the crossover feature. A British IPTV reseller can apply a low-pass filter (crossover) to redirect bass to the LFE channel. Without it, your receiver does the work.
What actually works for correct bass management is proper crossover in the stream. Your subwoofer gets only the bass it's meant to play.
My British IPTV had bass playing from main speakers AND subwoofer (double bass). Muddy. Switched to a reseller with proper crossover. Clean bass now.
The pattern that keeps showing up is that IPTV reseller UK operators with proper crossover are rare. Most send full-range and rely on your receiver to manage bass.
Honestly, if bass sounds muddy, ask about crossover. A IPTV reseller UK who implements it has better audio engineering.
That said, most AV receivers handle crossover perfectly. Reseller crossover is unnecessary.
In most cases, British IPTV subwoofer crossover is handled by your AV receiver, not the reseller.