This happens quite often at work.
The customer comes in and says they can't connect wirelessly.
We test the connection and it works fine in the shop.
Then we discuss their internet connection, router. and ISP
Often we get "I don't have a router."
Then we gently break the news to them that they were most likely leeching off of their neighbor - and when the neighbor caught on he put some security on the connection so they couldn't connect. We also advise them that their personal information may have been compromised, so they need to be aware of any issues with their personal information.