Abnormal Block Connections and Intrusion Attempts

Hi Everyone, Recently there has been multiple intrusion attempts on my computer from IP address 68.183.XXX. XX similar to mine, which is only a difference of the last two numbers. In fact when I looked up the IP address it belonged my ISP. There was a total of 10 intrusion attempts from this same IP “intruder” address within 20 mins, along with barrage of blocked connections - again from the same IP address to various ports (ie. 5357, 2869, 139, 135 etc). Although this only lasted an hour (the blocked connections and intrusion attempts seemed to to have stopped) I’ve never had this happened before, and the only threats Norton detected were tracking cookies since the beginning of this year. Is this a false positive or should I be genuinely concerned? Any feedback would be appreciated. (PS. Also what’s the difference between an intrusion attempt and a blocked connection.) Milo