It sounds like your box has failed.
I have raised to the OCE for you but as it's Christmas it may take longer to respond than normal.
Can you please add your home phone number to your Community Profile so I can locate your details.
If unsure of your number, simply dial 17070 from your land line phone and this will confirm the number for you.
Please reply when this has been updated.
Can you try a different ethernet port on the router, and also try a Youview Maintenance Reset (Option 2: Keep Recordings). This will clear any issues with the box memory and cached files and then we can see if the same behaviour persists.