guest network ac51u

I have got sky fibre broadband and i want to add a guest network to this as when we have partys certain people who are logged into my wifi start sending music to my airplay / dlna devices as they think its funny, lol

I have purchased a asus RT-AC51U router and using the wan port connected it to my sky hub (not sky q)

I am trying to set it up as an access point and it all works fine, but if i enable guest and use another phone and login to the guest network i can still see all my network...

guest network ac51u