If someone walks on my property without my permission, he is trespassing, a misdemeanor that can be punishable by a court of law. If he USES my property without my knowledge and permission, that is even worse. How can there even be a question about it? I happen to be totally ignorant regarding WiFI or whatever it is, how it works, what it is meant to do, so I really speak from a place of lack of information. However, if there is any chance that using something that belongs to someone else is being done without permission, whether it injures that person or not (causing a loss to him however minor), it is not the quality or even quantity of loss that makes it gneiva. It is still called gneiva whether you steal a penny or a million dollars (though arguably the million will probably hurt a lot more). The person might be MOICHEL on his loss, but that does not give one the right to make that decision for him. I cannot imagine the halacha being otherwise. Don’t knowingly steal someone’s WiFi. Now will someone please explain to me how this is even done????????