So my home network is absolutely

ed. Modem looks like it is working fine, but I can't get anything to connect wirelessly. I can't even get a connection when I hard-wire my laptop straight into the modem. So now I'm stuck waiting for them to send me a new modem. I partially think this is Comcast intentionally screwing me so I will use their new modem, which they've already been bugging me to do for months.
So right now I'm on the free xfinity wifi hotspot that is next to my house. What is this even? Can somebody explain to me where this wifi is coming from? It's also "open" so is it still ok to log into things like my bank accounts using this open connection? Thanks.