Comcast sets up “hot spots” using their customer’s wireless. Not being a Nice Person, I did away with that when I bought a modem. It may be someone in a car parked nearby, although since he got into you PC for some time, probably not.
The OP sent me some more information that makes this look like Apple sending notifications to apps that are running on the OP’s computer. It does not appear to be hacking of any sort.
I am going to close this. The OP may continue to contact me via PM about this issue if he desires.