Hi,
This has been driving me cazy since receiving my Talk Talk box. Fortunately it's not on my main TV and I'd certainly never rely on it.
I'm exactly the same, all TT router and powerline adaptors. The box is connected to the internet at a good speed and I can receive all the various internet players without problem.
If I go through the procedure of turning everything off and booting up in the right order, the Sky channels return. However, inevitably I lose the channels again after a few days or weeks and have to go through the same procedure.
The help line and TT operators are great but the equipment and infrastructure is useless. I'd never pay for these boosts.