|How was I supposed to know he was a tenant? Many landlords offer cable TV & an internet connection as part of the lease. If you don't, that's up to you.|
As far as the tech part goes, if it's not wireless, there must be a jack in his room. Otherwise, he couldn't connect. Is that correct? If it is, disconnect the jack.
If it is wireless, use MAC address filtering & encryption.
How do you know when a politician is lying? His mouth is moving.