I honestly don't know what to do about this?
I'm not an IT professional, I'm a mechanical engineer. But I am responsible for all the IT in my house. I use a Sky router modem, because as far as I know I have to. I use powerline adapaters with encryption and wifi with encryption. My NAS, my Sky box, my TV and desktop are wired connections via the powerline and my tablet and phones are wifi. With the best will in the world I don't know how to improve the situation, I'm guessing my router has a generic admin password but I can't remember if that's something Sky let's me change.
No-one involved in the process of recieving and purchasing this stuff has ever suggested I need further measures to make it secure. It's a very unfortunate situation to be in.