If you get to watch movies on Rakuten TV Player, but there is no sound... here is the solution!
- Go to your iPhone or iPad's settings.
- Make sure your side switch is configured this way: Settings> General> "Use side switch to"> Mute. (If this is not the case, select "Mute").
3. Once checked this, try switching your iPad's side switch:
If you get the same icon as in the screenshot below, everything should now work!