Why was there a High Severity Intrusion attempt on my laptop?

[The Phlebob]

For information purposes, find out the details of the "intrusion", but note the word "blocked." Norton stopped it. That's what it's supposed to do.

There's no way to prevent any of fifty million potential hackers from trying your IP address once in a while. A router, if it has its own firewall turned on, tends to prevent them from even getting to your machine and its firewall, but apparently this one did. (Keep both working. Two walls always offer more security than one.)

Don't panic. Hackers often set their machines to trying hundreds of sequential IP addresses looking for weaknesses. This is part of modern living.

Hope that helps.