Windows 11 · Research guidance. Instructions are based on publisher guidance; a UK IPTV account was not tested on this platform.
Use the difference you already observed
If ordinary system sounds work but one app is silent, Microsoft identifies app-specific volume and output choices as useful checks. That observation narrows the question but does not prove the app is at fault. Note which app is affected and whether its own player mute control is already off.
Open Volume mixer
Microsoft documents Settings, System, Sound, Volume mixer. Under Apps, locate the affected application. Inspect whether it is muted and read its level without immediately moving every slider. Keep the system volume at a comfortable setting in case the app’s sound returns suddenly.
Review the app’s destination
Microsoft says an app can use an output device different from the system default. Inspect that app’s Output device in the mixer. A programme routed to another connected output can be silent at the speakers you are listening to even when the computer’s ordinary notification sound is audible there.
Repeat the same spoken sample
After one deliberate change, use a short passage in the same app. Avoid changing the player volume, system level and output destination simultaneously. Record whether the result changed. A working system chime is a useful comparison but is not a full test of every app or media format.
Keep the next step proportional
If the app is unmuted and routed correctly but silence remains, preserve those findings. Microsoft’s broader guidance includes further audio investigation, but a driver or service change should have its own reason. Do not reset every audio component or service account merely because the first mixer check did not solve the symptom.
Questions, answered
Can an app use a different output from Windows’ default?
Yes. Microsoft documents a per-app Output device choice.
Should every volume slider be raised to maximum?
No. Keep levels comfortable and change one relevant control at a time.