I have previously posted issues with sound loss when using FF on recorded Internet channels like BT sport. If this happens the only way to get sound back on any channel is to physically switch the box off using the rear switch and then turn it back on. I have now seen issues with All 4 when watching F1. After a commercial break the sound may go off. To get sound back you have to exit All 4 and put the box into standby using the remote and then turn it on again. Going back into All4 the programme can be resumed and sound returns. It doesn't happen each time there is a commercial break but it is very annoying. I also noticed that if you exit All 4 under these circumstances it is not possible to view the terrestrial HD channels but the SD channels can be viewed. When the box is turned on the HD channels can be viewed. I was watching iplayer today and the internet connection to the box went down, although other devices were OK, and again it was not possible to view HD channels as described above after exiting iplayer. The box had to be switched off and on using the remote to recover them. Not impressed with You View Boxes!
We have 4 YouView devices in our home, none of which display the issues your having. So you most likely have an induvidual home network issue.