doing what it is doing now prior of your comcast?

If it is not .. then your comcast Wifi is the cause.

If your mouse have the problem before your comcast wifi.. then it is your mouse or pc problem.

To use other people Wifi (whatever the term is, checking, testing, stealing eyc.) just disable your WiFi.. and try to connect to any available network .. if you can browse . then it is an unsecure connection.

Who is that belong to?? God only knows... but most likely... 1 or 2 houses from your location.