YouView boxes tend to be fussier about the signal strength than TVs do. It doesn't help that the YouView box has twin tuners to feed. You may need the aerial adjusted or upgraded.
So recently got the BTTV UHD YouView service, the issue I've been facing is with the freeview channels. When the aerial is plugged in to the box, all the channels start scrambling, rescanning the channels doesnt help. When the aerial is plugged in directly to the tv the channels are perfect and don't scramble at all. I wonder what the issue is any body else had this?
Take a look at the following:
We’re aware of an issue some customers have experienced where their STB does not pick up all of the DTT TV channels that their TV does. This is often a result of the TV aerial lead to the STB being put under stress, for example being pushed against the back of a TV cabinet introducing a tight radius bend. It may also be because of interference from other electrical devices. If you find you’re having this issue try altering the path of your TV aerial lead, eliminating any tight bends near the STB, and keeping the lead away from interference sources.