In our school we made a submarine. The inner hull is a few cm thick metal, so it should be a good farady cage, but it does not act like one when blocking wifi from inside the hull. Wifi antenna is not touching the hull. The hull acts like a faraday cage when blocking a phone signal from the outside the cage. My question is, why does the hull not block wifi signal comming from inside the hull, but does block other signals comming from outside the hull.